Engine Won't Crank - Battery is Good

[handypilot]

Originally Posted by behlinla

When the car is in RUN, you shouldn't have any voltage on terminal 85. The only thing might be if the voltage is back feeding through the radio. Remove fuse #27 (5A) and repeat the test.

Removed fuse #27 and the voltage at Terminal went from ~10V to slightly less than 12V (~11.9V) with the ignition in RUN. However, it was less than battery voltage which is currently 12.5V. It still increases to current battery voltage with the ignition in START.

[behlinla]

Are you testing with the relay in or out? Should be out for this testing.

Again, there should not be any voltage at terminal 85 in RUN, so something is up. Unplug the TRS and see if it goes to zero.

[handypilot]

Originally Posted by behlinla

Are you testing with the relay in or out? Should be out for this testing.

Again, there should not be any voltage at terminal 85 in RUN, so something is up. Unplug the TRS and see if it goes to zero.

Relay is out when testing for voltage.

TRS seems to be doing its job, voltage is zero in everything but Park and Neutral. The 10V in RUN can be measured all the way back to the central j-box at fuse #37. If I disconnect the TRS, I'm still getting voltage (less than battery voltage) at fuse #37 in the RUN position and then it goes up to battery voltage when you go to START. I suspect the problem is upstream of fuse #37...got any extra wire diagrams?

[behlinla]

Just to be clear, you are still seeing 10V at fuse #37 with the key on with the TRS unplugged? This means the voltage leak is upstream like you thought.

The power for that fuse comes from the ignition switch. There is another circuit that branches from that, so try removing fuse #38 to see if the voltage is coming from that other circuit.

The ignition switch is on the last page. The down arrow next to fuse 238 goes to fuse #37 and the TRS (circuit 50).

http://www.revbase.com/BBBMotor/Wd/D...e-1579e3eb8a54

[handypilot]

Originally Posted by behlinla

Just to be clear, you are still seeing 10V at fuse #37 with the key on with the TRS unplugged? This means the voltage leak is upstream like you thought.

The power for that fuse comes from the ignition switch. There is another circuit that branches from that, so try removing fuse #38 to see if the voltage is coming from that other circuit.

The ignition switch is on the last page. The down arrow next to fuse 238 goes to fuse #37 and the TRS (circuit 50).

http://www.revbase.com/BBBMotor/Wd/D...e-1579e3eb8a54

Yep...power at fuse #37 with the TRS unplugged.

I pulled Fuse #38 (5A) and the voltage at Fuse #37 is finally zero in RUN and battery voltage (+12V) in START, so obviously this voltage is coming through Fuse #38. I looked it up and this fuse is for the GEM Park/Neutral Switch. I did a quick search and found that this switch may not exist in my car (because of the TRS) but there could be other items protected by this fuse.

I tried looking through the wire diagrams on autozone.com to find more circuitry connected to Fuse 38 but had a hard time finding anything as the diagrams are not searchable.

Any insight?

[handypilot]

One other thing to mention...

When the car doesn't start it seems to lock up electrically also. What I mean by this is when the ignition switch is initially placed in the RUN position everything electrical on the interior seems to work, as soon as you turn the ignition to START the car electrically locks up and nothing in the interior works no radio, lights, power windows or locks, and the dash goes really dim.

Also...
I pulled Fuse #38 to see what items it may control and everything works in the car's interior and the car starts and runs fine.

[behlinla]

It took me a while to find, but fuse #38 just runs straight to the GEM. Nothing else. So I'm not sure if that suggests the GEM is bad or not, but I don't think you should have voltage back feeding on that fuse.

I guess take the fuse out (should be tan 5A) and put it in the glove box. See if you notice anything not working for a few days.

If you have access to a scan tool, it might be worth scanning the GEM for any codes. A dealer can do this for you.

I should also ask if you have any aftermarket electrical devices added to your car that might possible be tapped into that circuit?

[handypilot]

Originally Posted by behlinla

It took me a while to find, but fuse #38 just runs straight to the GEM. Nothing else. So I'm not sure if that suggests the GEM is bad or not, but I don't think you should have voltage back feeding on that fuse.

I guess take the fuse out (should be tan 5A) and put it in the glove box. See if you notice anything not working for a few days.

If you have access to a scan tool, it might be worth scanning the GEM for any codes. A dealer can do this for you.

I should also ask if you have any aftermarket electrical devices added to your car that might possible be tapped into that circuit?

I don't have anything aftermarket installed on the car at all. I was wondering about the GEM...I took it out to get the part number just in case I need a new one. I took out the GEM to see where the weird voltage was coming from, and it is definitely coming from the GEM circuit board (the right side of the fuse terminal).

We'll see how things go with Fuse #38 removed. Thanks for all the help!

[behlinla]

Yeah, as far as I can tell fuse #38 doesn't really do anything. Some people don't even have a fuse there from what I can find (could be some kind of legacy circuit).