key system does not work

2002 DODGE CARAVAN

150,000 MILES

ROWLAND STEVENS

MEMBER
1 POST

Starter works relay works (just overall hauled solenoid) when you turn the key, clock light dims but starter doesn't click or run.
My specific question is in the key tumbler in the back is a hole with a white nylon rod inside about an 8th of an inch.
I saw a picture of another one but its (black rod was sticking out the back. When I turn my key tumbler to start position nothing happens to that white rod
could that be why in start position it does nothing?
Of course, the rectangular portion that goes in the switch assembly does turn when you turn the key.

Feb 9, 2022 at 5:10 AM

KASEKENNY

✓Experienced Mechanic
18,907 POSTS

You could be onto something, but I would suggest we try to jump to the relay and check for voltage to find out if we have an issue with the ignition switch.

Basically, all the switch needs to do is supply power on pin 86 of the relay.

So, remove the relay and turn the key and check for voltage here and if you have 12 volts then the ignition switch is fine.

Here is a guide that will help with this:

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

If you have 12 volts here, then we need to jump over to pin 85 and check for ground. This is where I think the issue is.

Put your red meter lead on battery positive and the black on pin 85 and crank the engine. If your meter reads 12 volts then the PCM is grounding the relay and commanding it to close and start the engine.

If the PCM is not grounding it then this could be the PCM but more than likely you have an issue on the T41 circuit which is common on these vehicles. This is the transmission range sensor and tells the PCM that the vehicle is in park and is okay to start.

However, let's get to that once we prove this out and go from there. I attached the wiring diagram below so let me know what questions you have.

Thanks

Image (Click to enlarge)

Professional Diagram for 2CarPros Members
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Feb 10, 2022 at 8:09 AM

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