Friday, July 28, 2006

1999 Jeep Cherokee AC is leaking water in the passenger floor and has no engine codes.

Vehicle engine code question:

I have a problem on my 1998 Jeep AC which has occurred in the past week. The front passenger floor get wets after I used the AC for over an hour. Everything is working fine and I have cold air in the vents. I also scanned the code but there is none. I don't believe it is the heater core and my engine is not overheating. Can you help?

Vehicle engine code answer:

There is a service bulletin for this problem which calls for servicing the drain tube located at the bottom of the AC evaporator case. This evaporator is located under the dash panel in the passenger side. You can pull up the carpet of the passenger side to access the tube and drill a small hole on top of the tube. Use a 1/4 drill bit and blow air to the hole you made to clear the blockage in the tube. Don't drill right thru it and do it at the lowest location of the tube. The hole can be sealed with silicone after clearing the drain tube.

To get the service bulletin for this repair, contact your local Chrysler dealer or ATS.

Tuesday, July 25, 2006

P0401 engine code for 99 Honda Accord


Engine code question:

I just joined ATS and using my scanner, I got a P0401 code on my 1999 Honda Accord V6 engine which is for insufficient egr flow. How do I proceed to repair this code?

Engine code answer:

This problem is common on this type of engines. The egr valve on this does not usually go but the passages get easily clogged with carbon which need to be cleaned. You don't even have to do anything on this because Honda has a recall on this job. All you do is call your local dealer and give them the serial number of your car and they will fix it free for you. This is covered under Honda emission warranty.

In case there is no warranty, let ATS know and we will send you the step by step info on how to clean the passages.

Monday, July 24, 2006

P0303 misfire code on 97 Silverado truck with 5.7 vortex engine


Check engine code question:

Using my diagnostic scanner, I found I have a code P0303 (cylinder #3 misfire) on my truck. Initially, I have tried changing plugs and plug wires with same results. The compression reading is the same for all cylinders. I suspect the injectors might be the culprit but the job involved is too much which requires removing the intake manifold. Any other test I can do before I do this?

Check engine code answer:

You never mentioned if the distributor cap was replaced on this but this problem is very common on this model. Just make sure that you use AC Delco parts not the aftermarket parts. With regards to your injectors, try checking the internal engine vacuum reading first by plugging the vacuum openings (pcv and vent hole) on both valve covers. Install a vacuum gage in the oil dipstick tube and see if you get any vacuum when engine is on idle. If it does, your intake gasket is leaking.

If intake gasket is OK, the injectors can be removed and checked for spray pattern and compared to each other. This is done by removing the upper intake and lifting the injectors. For more details, please contact ATS so I can send you the wiring diagram.

Saturday, July 22, 2006

1999 Isuzu Rodeo 3.2L engine has no fuel signal.


Car wiring question:

I am an ats member and my son’s 1999 Isuzu Rodeo won’t start. I checked the fuel signal using the noid light tester and it was not blinking. I have a crank sensor code which made me replace the sensor but that did not help either. I then replaced the computer thinking that was the culprit and still the same…no signal to the injectors! I am losing my money and sanity here please help!

Vehicle wiring advice:

Always go to the basics before buying any parts for your engine. The way this system works, when the computer (ecm) works, it gets its power from the main relay thru the relay’s red white wire, which goes to the ecm B+ pin terminal. That main relay also houses the fuel pump relay, which feeds 12 volt to the fuel pump thru red wire when you turn the key on. However, looking at the wiring diagram, the ecm powers also the coil plugs (a combination of the spark plug and ignition coil) thru ecm pin F4 then individually grounding them.

To check the ecm, check the ecm power supply from the main relay at pin B+ during cranking. There must be 12volts there. Also, the reference pins at the ecm terminals must have 5 volts and double check against those reference volts at the input sensors such as the tps, coolant and map sensor. Failure to have those 5volts reference shows that the ecm has failed.

Notes:

Reference voltage can fail also if the ground pins at the ecm shows more than 0.250 volt with key on. These ground pins are C7, C8 and C9. Any pins showing more than 0.250 volt shows there is a short in the wire, sensor or any output loads.

When working with any electrical component, disconnect the battery negative terminal.

Friday, July 21, 2006

2000 Ford WindStar with P0401 check engine code

Vehicle Question:

I have this nagging P0401 code (insufficient egr flow) on my 2000 Ford WindStar. I have tried resetting the code but it came back after I got the van running a few miles. And when I check the vacuum going to the egr valve, it seems to have a flow there. Help!

Vehicle Question Answer:

Whenever you have this code, the DPFE sensor must be changed because it has a high rate of failure. You can also use a voltmeter and monitor the voltage of the DPFE signal or input wire: it should read about 1 volt with engine running at idle and if you apply vacuum (use a hand held vacuum pump) to the egr valve, the reading should move up to approximately 4.0 volts. If there is no change, replace the DPFE sensor.

For more details on dpfe sensor, contact ATS. Also make sure all vacuum hoses are free flowing and not clogged.

Wednesday, July 19, 2006

2001 BMW 530i has no check engine light code but AC does not work?


Vehicle Problem:

I am a member of ATS and my BMW 530i has no AC. As per your instruction regarding resetting the AC control unit, I removed the battery terminals and joined them together but still my AC does not work. Also, when I checked the control unit, it does not send power to the compressor clutch. I had a garage get the code for me and they found none. What do I do?

Vehicle Question Answer:

To give you some basic principle on your AC, your controller controls your AC compressor by supplying power to your compressor clutch. It does this after reviewing all the inputs like engine speed, freon temp and pressure, etc. To check, make sure there is power and ground going to the control unit. Then check if the control unit is sending power to the clutch wire after you turn it on. Sometimes, the control unit needs resetting and you can do it by touching the battery terminals together at least 30 minutes. This should wake up the sleepy controller and you can verify that by checking the clutch wire again.

You need a wiring diagram to fix this so you can identify the wires involved. ATS will supply it to you if you ask for it.

Sunday, July 16, 2006

1998 3.0L engine Ford Taurus no crank starting problem


Car wiring question:

I am an ATS member and I wonder if you can help me. My 1998 Ford Taurus will not crank. Using a test light, I cannot get any power going to red and white pink wires at the starter solenoid. I can manually crank it if I jump the white pink wire. A mechanic friend of mine installed a new ignition switch but the problem is still there. We also disable the remote starter thinking that is the culprit but again, no cranking. Can you suggest anything?

Vehicle wiring advice:

This problem is very common with the starter solenoids having bad contact causing the starter intermittent problem. This starter solenoid is located in your starter housing. Wait first for the symptom to get worse so you can catch it on the act. To test, make sure you have 12 volts power supply going to your black red wire. That wire comes from the starter relay located in the left side of the engine compartment. If there is no power in the wire, it means the starter relay is the problem. Otherwise, the starter solenoid is the problem.

You can service that solenoid by replacing the contacts. They cost about $20 and is cheaper to repair than replacing the whole assembly. Remember to disconnect the battery negative terminal before removing the starter.

Notes:

It is preferable to use a wiring diagram when tracing your starting circuit, should you have any difficulty, ats can give you complete descriptions on the wirings.

Saturday, July 15, 2006

2000 Jeep Grand Cherokee with 4.0L engine cooling fan won’t engage

2000 Jeep Grand Cherokee with 4.0L engine cooling fan won’t engage

Car wiring question:

I just subscribed to ATS to be able to help my daughter who bought a 2000 Grand Cherokee from an auction. She said the price was pretty cheap and she thought she got a good deal because both inside and out of the car looks clean. However, after picking it up from the lot, it seems to run abnormally hot. I had the cooling system checked and it seems somebody already replaced it with new radiator and thermostat.

What they did not correct is the cooling fan won’t engage as soon as it gets hot. I think this problem is only in the wirings or some electrical components; can you guide me in the right solution? I will appreciate it very much.

Car wiring advise:

Looking at the wiring diagram, your cooling fan has 2 wires: dark green wire which is your supply wire 12 volts and black pink wire which is your ground wire. Check the ground wire first by making sure that it is fasten tight and not corroded at the right hand headlamp area. The supply wire comes from a fan relay, which is located behind the bumper also in the right hand headlamp area.


You might have to remove the bumper to do this fan relay. Just make sure that with your key on, there is power going to the grey wire in the fan relay and when you reach the hot temperature, that dark green wire from the fan relay kicks in. Otherwise, you need to replace that.

Friday, July 14, 2006

1999 Toyota Camry 3.0L brake lights turn on when turn lights are on


Car wiring question:

Last week, I bought this 1999 Toyota Camry thru a private deal and the price was so good I could not let it go. The previous owner took good care of it and besides this minor problem, the whole car looks immaculate. The problem is when you turn the signal lights on, the brake lights also comes on. I looked at the brake switch above the brake pedal and it tested good. Can you shed some info as to what is causing this?

Vehicle wiring advice:

It seems to me that you have a shorting wire going from your turn signal light circuit to the brake light circuit at the rear of your vehicle. These are the possible ways it can happen:

Using a single-filament bulb 1156 instead of two-filament bulb 1157. Collapsed bulb sockets on two-filaments bulbs Crossed wire connections when repairing the lights at the rear of the vehicle. Shorted wiring harness in the trunk area especially near the hinges. If you have a trailer hitch harness on this, check the wires for bare insulations. Head light switch could be defective.

Thursday, July 13, 2006

2002 Jeep Cherokee misfire with P0303 code


Vehicle Question:

I just joined ATS because I have a code P0303 on my 2002 Jeep Cherokee. This denotes misfire on cylinder #3. So far, I checked #3 compression and it was the same as the rest. I also ohmmed out the #3 injector and it has the same resistance compared with all injectors. I cleared the code using ALL-IN-ONE scanner but it came back after driving the vehicle for a few miles. What do I do except going to the dealer?

Vehicle Code Question Advice:

This code is very common on this model because of the proximity of the #3 injector. After the engine has warmed up, the heat generated by the engine is mostly directed to #3 injector causing the fuel in the #3 injector vicinity to boil causing the misfire. Chrysler has a shield kit to repair this problem if you see them so you can install it yourself. Once you do this, the check engine light code should not return.

Wednesday, July 12, 2006

2002 Toyota R4V4 fault codes P0420 and P0430

Vehicle Question:

I own a 2002 Toyota R4V4 and using my all-In-One Scanner, I get two fault codes: P0420 (Catalyst effeciency low bank #1) and P0430 (Catalyst low bank #2). Watching the rear oxygen sensor reading on the scanner,it looks normal.Also,the reading was switching back and forth at idle.However, after I reset the codes, the codes came back.Any suggestion?

Vehicle engine code advice:

There is a TSB regarding these codes (Toyota service bulletin #EG010-02 explains the correction's for these codes) and it calls for upgrading or reflashing of your engine computer by the dealer. This service is offered FREE and all you need is book an appointment.

Your rear oxygen reading is not supposed to switch at idle and that would indicate a CAT failure.Usually, the oxygen reading will osciliate only after 1500 rpm but not on idle.Have the dealer upgrade the computer first and followed that by CAT replacement which is covered under 8 yrs or 80 miles warranty.

Note:

Make sure you have done your regular maintenance like plugs and filter change before you see the dealer.

Monday, July 10, 2006

1998 Ford Taurus radio quitting when put in reverse.

Car wiring question:

Three months ago, I bought a used 98 ford Taurus from an auction lot. I plan to use it for my kid going to college. The last 2 days, the kid told me that sometimes, the radio quit when she put it in reverse. After that, the power steering goes haywire too. I confirmed this myself and it seems the engine and other components of the vehicle are fine except these 2 things. Is there something I can do here except to bring this car to a garage?

Vehicle wiring advice:

You do not need to bring this car to a garage because this problem is common! First of all, what is happening right now is your GEM module (another name for body computer) is acting up because one of the sensors it controls is defective. That sensor is called TRS sensor, which stands for transmission range sensor. Another equivalent of this sensor is your old neutral safety switch.

If the TRS sensor is defective, it will send a faulty signal to the GEM module, which will make the GEM module, shut down your radio and sometimes other accessories such as your power steering, power windows, false dash readings, etc. This sensor is located on the top right side of the transaxle. Before replacing this sensor, make sure to check the wiring harness connected to it is not rubbing any metal. Also count the pins on the sensor because you will need that when ordering the part.

Unfortunately, this sensor can be bought from the dealer only and you have to ask them for the updated part. To avoid comebacks, some garages will replace the GEM module too but try the sensor first to save you some money.

Sunday, July 09, 2006

1999 Toyota Camry 3.0L engine has no spark and fuel

Car wiring question:

I bought this car three months ago and the other day, it quit on me. Reading your lessons I found there is no spark and no fuel. As indicated in the lesson, this shows I need a new computer. However, the computer is a little bit pricey and I want to be sure if that is the culprit. Is it possible also that all I need is just the efi relay?

Vehicle wiring advice:

For almost all engines, if you have no spark and no fuel, almost always indicates a computer failure. However, in this model, both spark and injectors bare controlled by the ignition module called igniter. The igniter inturn is controlled by the computer so it is possible the igniter maybe the culprit here.

To check the computer, go to the computer terminals and check these terminals for power: pins +b and e1. You should have power there. Then check pin MREL and pin BATT that are used to power the efi relay. If you do not have power on these last 2 pins, then definitely, the ecm is bad.

One quick way to check if the ecm is bad is by using your dash light. When you turn your key on, there should be power of “check engine” light and quit. If the light fails to come on at all then for sure the ecm is no good.

Notes:

The efi relay is use to power your fuel pump but the injector gets its power from the igniter.

Before replacing the ecm, just make sure the computer ground wire pin NE is not shorted.

When disconnecting any electrical components, always disconnect the battery negative terminal.

Saturday, July 08, 2006

1997 Nissan Pathfinder 3.3L engine with remote key chains stopped working

Car wiring question:

My son’s 1997 Nissan Pathfinder remote key won’t lock or unlock the doors. We thought the battery of the remote was dead so we installed a new battery but it’s still the same. I am not sure if this remote control has to be reprogrammed or not. If it is, do you have a procedure handy to do this? Thanks for your help.

Vehicle wiring advice:

Like anything else, your key chain remote control can be worn out and you can re-program it. A computer controls your remote system called “smart entrance control unit” located behind the dash on the right of the steering unit. To check the system like any automotive computer, check for presence of power thru pin #1, which is a white red wire. There should be 12 volts there with key on. If not check the circuit breaker located at the left kick panel. The ground terminal is located at pin# 5 and has a black wire. Again don’t exceed o.250 volt there or there is a short in one of your power lock switches or wires.

Once you have confirmed this, you can re-program the remote this way:

Enter the driver seat and close and lock all doors. Insert and remove your ignition key for about 7 times in 10 seconds. If successful, hazards lights will flash. Turn ignition switch to ACC position and push any button of the remote. Hazards lights will flash if the programming is successful

If you program your old remote this way and still it will not work, replace it with a new one. Any additional remote, you can program it by unlocking and locking the doors with the door internal switch and press any button on the remote.

Friday, July 07, 2006

1999 Chevy Blazer 4.3L engine has weird no start problem


Car wiring question:

I have been driving this 99 Chevy Blazer with 4.3L engine, auto and for the last week, it would not start for me sometimes. When this happens, these weird symptoms occur: My dash lights will not come on and my trany shift lever won’t come out of park. I used your wiring basic visual checks and I found I have good battery voltage and I can hear the fuel pump running. When I tested the fuel pressure, it seems to be in the right range and all my fuses are good and there is no code. If you wait for a while, it will just starts! Any ideas?

Vehicle wiring advice:

Whenever your engine won’t start accompanied by no shifting, the usual culprit is the ignition switch. To check, check the purple wire along your steering column wiring harness and see if you got 12 volts there when you start it. If none, most likely the ignition switch is faulty. You can double check that by checking also the purple wire at your transmission “range” switch located on the left side of the trany. If there is no power there too, then for sure change your ignition switch by all means.

Notes:

Ignition switch can be replaced without removing the steering wheel. You can lower the steering column by removing the 4 bolts located under the dash to gain access to the ignition switch. Same switch should be available in your local parts store.

To avoid buying unnecessary parts, do your usual no spark and no fuel tests as described in ATS past newsletters.

Sometimes after the ignition switch installation, the body computer has to be reprogrammed if the engine still won’t start. Other times, it might not be necessary. Please let me know.

Thursday, July 06, 2006

1997 Ford F150 Pick Up 5.0L engine with abnormal battery drain


Car wiring question:

I noticed my engine is struggling when started during cold weather. Yesterday, I tried to measure the battery drain as described in your test and it was close to 0.250 volt. This is strange because I just put a new battery in this truck 6 months ago. Do I have a problem here? I am just worried that this vehicle might leave me stranded but I don’t want to change any parts if I have too.

Vehicle wiring advice:

For 1997 Ford models, a device called "GEM"controls your battery which stands for Generic Electronic Module. What it does is control all kinds of little gadgets in your vehicle (the ECM controls only the engine). One of them is called a battery saver relay. Here is how you can properly test your brain drain:

Hook up your digital voltmeter between the battery negative post and disconnected battery negative cable. If you get an extra higher voltage reading like 0.250 v, wait for about 1 hour and the GEM control will stop. This shows that the GEM module is OK.

In case the battery readings remains high after the above test, try these:

Load test your battery strength level using a battery tester described in ats past newsletters. Put a battery charger on it for at least 2-3 hours. Measure the battery strength level again.

If the battery strength remains the same, you know for sure the battery is no good. Otherwise, there is a definite battery drain in your system.

Wednesday, July 05, 2006

1997 Chevy Cavalier 2.2L heater blower motor stuck on high speed!

Car wiring question:

My heater fan blower motor is stuck on high speed only. I know there is other speed likes low and medium which is indicated in the dash controls but it remained on high speed regardless of the position of the control knob. I really want these features to work because sometimes, it really gets so hot inside the car. Checking with a friend mechanic, I was told there is a resistor or relay associated with this. Can you send me some info with this problem?

Vehicle wiring advice:

Yes, the relay and a resistor are a part of the blower circuit to control the fan speed. The blower motor relay is located on the left center of the engine compartment. The blower resistor is located under the center of the dash. Your fan speed might be caused one of these 3 components:

# Defective blower resistor
# Defective blower fan relay
# Defective blower motor switch located in your dash

The quickest way to check this problem is to check the resistor wirings. The resistor pack is located under the center of the dash near the glove box. It has four wires and if you put the voltmeter test lead on the orange wire, it should change it’s voltage every time you change the setting of the blower motor switch. If not, the resistor is defective which requires replacement of the resistor pack. This part is not expensive and is readily available from GM because it is a common problem.

Note:

The blower fan relay is located at the left center of engine compartment. If the resistor pack does not solve the problem that is your second choice followed by the heater blower switch.

Tuesday, July 04, 2006

1996 BMW 328i 2.8L engine has no spark and no fuel, is it the ecm?


Car wiring question:

I own a 1996 328i BMW with 2.8L engine, which I bought from an auction lot and a week later quit on me. There is no spark and no injector signals, which to me points to a engine computer failure. The computer is over a thousand dollars and before I spend this kind of money, I want to get a second opinion from you. Thank you.

Vehicle wiring advice:

Before condemning your computer (ecm), I would like to explain to you how this engine ecm control works. This system has a power distribution box, which houses the ecm relay and fuel relay. The ecm supplies 12 volts to both ecm and fuel relays thru pins 6 and 8 of the power distribution box shown by the red wire. This red wire comes from B+ terminal of the ecm shown as pin 26. This ecm relay also gets a ground signal from the ecm at pin 73 of the ecm which comes from pin 4 of the relay. This pin 4 is the brown wire. Once you turn the key on, your ecm activates both relays.

If the ecm does not supplies 12 volts at pins 6 and 8 and also not supply ground voltage at pin 4 then you can say the ecm is no good.

These are what your engine electronic system also does:

The fuel pump relay powers all the injectors thru the red wire after being activated by the ecm when you turn the key on.

The ecm relay powers all the ignition coils thru the red wire coming ecm relay after being activated by the ecm.

Notes:

This computer is known to fail cause by water damage after the cowl drain above it gets clogged with debris. To check, open the top cover of the ecm and check for presence of heat burns or corrosion.

Always disconnect the battery negative terminal when working with electrical components.

Sunday, July 02, 2006

1996 Jeep Cherokee 4.0L all gauges not working and no start


Car wiring question:

Hi, I am a new member and my jeep quit on me the other day. I know it going to cost me big bucks and towing to the garage that is why I subscribe to ATS. During no start, all the gauges lights in my dash quit and my neighbour mechanic tried disconnecting the battery to reset the computer. After resetting, nothing changed and we are stuck. He suspects the ecm is bad but we don’t want to guess because it is a little bit pricey. Please help.

Vehicle wiring advice:

From your description, it does seem to point to a computer failure but on this system, you have 2 types of computers, the engine computer and the body computer. The body computer (bcm) usually controls your dash panel. To test, try unplugging the engine computer (ecm) and see if the dash lights returns. If not, try unplugging each of the modules or components of the bcm. If the light returns this time, the last module you touched is the culprit.

These are some of the bcm modules: power doors, power windows, audio, anti-theft alarm or any options your vehicles have. You should see them in the wiring diagram or I can give you a complete list if you give me the VIN number.

Notes:

The bcm terminals pins can be tested individually just like the ecm. Please refer to ats past newsletters. Make sure the voltage to the power and ground wires are OK. Instead of using the reference voltage pin, use the bcm BUS connector to monitor how the bcm works. (The bus connector testing is discussed extensively in other articles shown here).

Finally make sure all the fuses are OK.

Saturday, July 01, 2006

1995 Cadillac Deville 4.9L heater blower motor not working


Car wiring question:

I own a Cadillac Deville and the blower heater does not work. I took out the blower motor to check it over in the bench and it has 3 wires. I supposed one is for power, another for ground and the third one is for something like a signal. When I feed 12 volts and ground to the 2 wires, it won’t work. Thinking it was defective, I bought a rebuilt one and it did the same. What is the deal here? Can I bench test this rebuilt blower motor?

Vehicle wiring advice:

Unlike other gm common blowers, this blower motor has a solid state control device inside to take a modulated variable voltage signal from a programmer (usually heater and ac programmer). This variable voltage is required in order to meet different speed requirements of your vehicle. Unless this input variable voltage is fed, it will not work during the bench test.

So what can you do? If you really want to check if the rebuilt blower motor is working, connect the battery positive and negative terminals direct to the blower motor. Then hook up a jumper wire to the harness where the third (signal) wire come from and it should run. If not, it means your programmer is defective.

Note:

Touching the third wire with a 12 volt supply might damaged the solid state controller inside the blower motor.