Hummer 3 Ignition Question

[Kymeth]

Hello,
I have a situation with the H3. I was just beginning to install a DEI brand keyless upgrade system to the vehicle, and was testing the voltage in the ignition harness. Now for some reason after testing the voltage the Hummer won’t start, or go into gear, and I keep hearing a “clicking” sound coming from the engine? I checked the fuses. Has anyone else ever had this happen to them? Any suggetion would be very much appreciated. The Hummer is at the dealer, I had to have it towed there and they have yet to even look or start on it to give me any kind of possible explanation and that was last Friday. Any suggestions would greatly be appreciated Thank you kindly...
Ky

[deicustoms1]

You used a multimeter to test, right? What did you need in the ignition harness for keyless entry?

Without knowing anymore, all I can say is triple check the fuses and make sure nothing came lose while removing panels and testing wires.

Tell them to fix your truck or give it back!

Btw - I think f5 will have an answer for you shortly.

[Kymeth]

Hi dei???????,

I used a 12 volt computer safety test light.
I went into the ignition harness for the
power source. I didn't remove any panels, or get to any wires...see, I never installed anything - I didn't get that far. Only used the test light and then found out that the vehicle won't start or engage...that's why this has me really frazzled.

Could it be the computer on the vehicle needs to be reset? Could it be the starter/solenoid?

I sure hope you or F5 can help me....

Ky

[deicustoms1]

Test lights are evil.

Did you try disconnecting battery for like 15 min? The test light could've given it a little voltage and, blew a fuse, triggered anti-theft, or initiated some system wrong and got it stuck.

Anyhow, for when you get it back. I recommened going directly to the battery for your power source. That's what I did, as the ignition harness is thin gauge and I didn't want to mess with it.

[f5fstop]

Originally posted by dei???????:
Test lights are evil.

Did you try disconnecting battery for like 15 min? The test light could've given it a little voltage and, blew a fuse, triggered anti-theft, or initiated some system wrong and got it stuck.

Anyhow, for when you get it back. I recommened going directly to the battery for your power source. That's what I did, as the ignition harness is thin gauge and I didn't want to mess with it.

I agree, with dei, test lights on electronic circuits are not only evil, but a bad idea. Electronic circuits draw milliamps, test light can draw amps. Too much current through an electronic circuit can fry something (also known as letting the smoke out of the box).
Always use a high impedance multimeter.
Here is a copy of a short, but to the point GM bulletin:
Test Lamp to Ignition Control Module Circuit Connector Notice
Notice: Do not leave the test lamp connected to the PCM IC circuit connector for longer than 5 seconds at a time. Failure to do so may damage the ignition coil and/or the Ignition Control Module.

Did you check all fuses in the circuit?
Batt IGN Fuse 5
IGN1 Fuse 33
STRTR Fuse 85

Then if those fuses are ok, check the following relays, you should be able to pull a relay from the A/C circuit or another circuit not required to run the vehicle and do a swap with one of the following relays:
RUNCRNK Relay 78
PCM CNTRL Relay 77

If all fuses and relays are ok, not sure what to tell you. It could be any number of items including, but not limited to a fried BCM or PCM; depending on which wires you were testing.

[Kymeth]

Yes, I did the battery disconnect and it
didn't help. I checked the fuses too.

I will take your suggestion when I do get
the vehicle back about using the battery
for the power source.

Thanks for the suggestions, I do appreciate it.

I just wish I knew what caused the vehicle to shut down like it did...

Thanks again,
Ky

[Kymeth]

Hi f5,

Thank you for all your help. I will do as you suggested regarding the relays. I will let you know what happens...again, thank you for your help.

I just hope I didn't fry anything...

Ky

[f5fstop]

Which wires (circuits) did you probe? Where did you do the probing?
That might help with some long distance, no guaranteed troublshooting.

[Kymeth]

Hi f5,

Okay the two wires I probed were the white with the black tracer on 12 volts constant. The wire was about 16 gauge. The second I probed was the ignition wire, which is the white with green and is located under the dash. It blew a 10 amp fuse and i did replace it, not sure if it was located at #18 on the fuseblock panel and it was a constant and I replaced it and now there is absolutely no constant to that feed panel on the fuseblock. Any ideas???

You have no idea how grateful I am for your help. Above all, I appreciate that I could confess my blunder here and get the immediate feedback and support that I did from you and dei???????.

Ky

[f5fstop]

Originally posted by Kymeth:
Hi f5,

Okay the two wires I probed were the white with the black tracer on 12 volts constant. The wire was about 16 gauge. The second I probed was the ignition wire, which is the white with green and is located under the dash. It blew a 10 amp fuse and i did replace it, not sure if it was located at #18 on the fuseblock panel and it was a constant and I replaced it and now there is absolutely no constant to that feed panel on the fuseblock. Any ideas???

You have no idea how grateful I am for your help. Above all, I appreciate that I could confess my blunder here and get the immediate feedback and support that I did from you and dei???????.

Ky

Where was the white with black, was that under the hood, or under the dash? If you did the under the dash wires, both circuits go to the coil side of the run/crank relay, through the 10A fuse 5 (BATTIGN SWITCH fuse). The white/black is between the ignition switch and the fuse, the white green is between the switch and the BCM Run Crank input.
That circuit is powered directly from the red battery cable to the fuse block, then through the bus. Do all the other accessories in your vehcle operate? If not, you could have damaged the bus in the fuse block, but I doubt that.
That circuit is direct from the battery, through the fuse.
I would double check the fuse again, check for power at the fuse, both sides, one side should always be hot, the other out of the fuse should not be.
Even if you blew a BCM, that circuit should always be hot with the battery connected.
Not sure where you probed. However, if you disconnected the large connector C201, check to make sure you didn't bend a pin upon assembly, very easy to do, I did it once.
Or, if you probed a wire, did you break it? Hard to do since that it a good size wire.
Only thing that comes to mind right now is a bent connector pin, if you disconnected the connector.

Send me a PM with your email address and I can send the power distribution wiring diagrams and the ignition diagrams. I'll do some more checking when I get to work.