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Mike S.
Mike S., ASE Certified Technician
Category: Cadillac
Satisfied Customers: 7433
Experience:  ASE certified
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I have a 2006 cts it wont engage the starter when the key is

Customer Question

i have a 2006 cts it wont engage the starter when the key is turned on and i cannot remove the key. I can turn the key on and pull out the starter relay and apply power to one of the sockets and the car will start. I can then reinstall the relay and turn off the car and remove the key. I can then start the car normally with the key for the next few minutes and turn the car off and remove the key. however, if the car sets for an hour and i try to start the car the starter wont crank and i have to pull the relay out and apply power again. I bought the car at an auction and i do not know its history. Also i do not have to jump the car the battery stays charged up.
simmons auto sales
Submitted: 2 years ago.
Category: Cadillac
Expert:  Mike S. replied 2 years ago.

I would try a new relay first.

Customer: replied 2 years ago.
Already did replaced it and still have the same problem.
Customer: replied 2 years ago.
I also tried a new key and that didn't fix the problem either.
Expert:  Mike S. replied 2 years ago.
Ok, let's take a more logical approach to this. First of all I would like to look up the wiring diagram, so what engine came in this?
Customer: replied 2 years ago.
Expert:  Mike S. replied 2 years ago.

Here is the wiring diagram,

Remove the starter relay when it's acting up and test the socket for voltage at each terminal. One spot should be hot all the time. That is the spot coming from the starter fuse and eventually the battery. A second should be hot with the key on start and start. That comes from the ignition relay, so let's begin with these 2 tests. Let me know the outcome.

Customer: replied 2 years ago.
On the starter relay socket one pin is hot all the time the other pin is hot in the run position the problem is that the pin that is suppose to go to ground in the start position does not. However, if you apply power to the remaining pin the starter will engage and start the car. Then the pin that is suppose to go to ground will work properly for the next ten minutes then it will not go to ground and the circuit will not be completed until the process is repeated.
Expert:  Mike S. replied 2 years ago.

Ok, technically it doesn't go to ground just yet, it goes to the ecm. Then the ecm grounds the relay depending of course on the crank signal from the ignition switch and/or the park/neutral signal from the transmission. Now, to determine which. I would gain access to the ecm and test for a voltage at pin 31 where the yellow wire comes in from the ignition switch in crank mode. Test it when the starter isn't engaging so you know the problem is occurring. If there is no voltage at pin 31, then it's a short in that yellow wire or the ignition switch may be bad. If there is no voltage test again leaving the ignition switch.

If there is voltage at pin 31, then test for a signal from the park/neutral switch at pin 32. This may be 12 volts or it may be only 5 volts. Also, the next time this problems happens try moving the shifter all the way from park to low and back and forth while holding the key on start. If at any spot the starter engages except park or neutral, then the transmission park/neutral switch is bad or needs adjusting, if there is even an adjustment for it.

Customer: replied 2 years ago.
I can't find the ecm to check the wires
Expert:  Mike S. replied 2 years ago.

The Electronic Control Module (ECM) is located to the left of the throttle body, and just above the drive belt.

Expert:  Mike S. replied 2 years ago.

Sorry, I was out.