Starter not working after replacing A/C controller

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coryforsenate

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Well %$$! me, this is the third time in the past six I've had an ignition switch go bad. The original lasted about 20 years. The GM one I installed about 6 years ago lasted 4 years, the generic one from the autoparts store lasted 2 years. Parts these days are such pieces of $hit. I always second guess assuming a fairly new part isn't the problem but it sometimes comes back to bite me.

I've got an open loop on

off position C1-D5
Start position C1-D1 and D1-D5

Since the replacement GM one lasted 4 years I ordered that same one, arrives tomorrow, rather than trying another autoparts one today that only lasted two years.
The resistor for the blower motor arrived today, will see if that fixes the blower motor.


It's not letting me post the picture but here's a link to the diagram I used
https://easyautodiagnostics.com/images/articles-600-699/680/682/image_3.webp

For anyone interested who's having the same problem, here's the troubleshooting steps I used, same as when I diagnosed the bad one two years ago.
  1. Disconnect the negative terminal from the negative battery post.

  2. Disconnect the ignition switch from the vehicle wiring harness connector at the base of the steering column.

  3. Place your multimeter in Ohms mode.

  4. Place the ignition key in the ACC position.

    You should have continuity between terminals D2 and D6 of the ignition switch connector.

  5. Place the ignition key in the OFF position.

    You should have continuity between terminals C1 and D5 of the ignition switch connector.

  6. Place the ignition key in the RUN position.

    TEST A: You should have continuity between terminals C1, C5, and D5.

    TEST B: You should also have continuity between terminals C6, D2, and D6 of the ignition switch connector.

  7. Hold the ignition key in the START position.

    You should have continuity between terminals C1, C5, D1, and D5 of the ignition switch connector.
Let's interpret your test results:


CASE 1: Continuity exists between the indicated terminals. This test result tells you that the ignition switch is OK and not defective.

CASE 2: Continuity DOES NOT exist between some or all of the indicated terminals. This test result tells you that the ignition switch is defective and needs to be replaced.
 

GoToGuy

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It sounds like you want to keep your truck for a while. For 20 bucks at rockauto you can get a pdf of your year factory service service manual. And it will guide you step by step, it kinda beats just throwing parts at it and praying. Just an idea to help out.
 

AK49BWL

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You do know about the relay next to the blower motor resistor pack that runs the high blower speed right... Also, one of the 40 amp fuses in the underhood fuse block runs power for that relay.

If you hadn't tested the ignition switch, I might have said check the Crank fuse in the dash fuse block. But that's crazy your ignition switch has failed that often...
 

coryforsenate

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Okay, good and bad news. Blower motor is now working after replacing the resistor. After replacing the ignition switch the starter still won't turn over via the key, only when I connect it to a live wire in the fuse box.
 

GoToGuy

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Have you checked by moving wiggle shift lever? Did you bump or touch any neutral safety switch wires.
 

AK49BWL

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How about trans position switch? If the computer thinks the trans is not in Park or Neutral, it's likely to disable the starter.
Computer doesn't have a say in the matter on the 400s. That switch is in line between the ignition switch and the starter relay tho, so it could potentially be the problem - your gear shift indicator should make this obvious, however.
 

GoToGuy

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Ignore the cracked case. Post office care in transit(not). What got from Rock Auto. Twenty and the shipping. Its in pdf so any computer can play it.
You must be registered for see images attach
 

df2x4

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It sounds like you want to keep your truck for a while. For 20 bucks at rockauto you can get a pdf of your year factory service service manual. And it will guide you step by step, it kinda beats just throwing parts at it and praying. Just an idea to help out.

FYI many of the GM factory service manuals can be downloaded in PDF format here for free as well.

https://www.gmt400.com/threads/88-95-service-manuals.43575/
 
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