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.