Annaleigh

Ok I did something really stupid. Just bought a 95 GMC Vandura G2500 and couldn’t find the ECM data connector. Supposed to be on the left side of the steering column, but instead there is this connector:
connector1.jpg Photo by Annaleigh_123 | Photobucket

It is like a pigtail and goes into another connector about 6” away, this one:
fuse4.jpg Photo by Annaleigh_123 | Photobucket

Don’t know where they go from there yet but it is something defiantly added. At the fuse block a set of wires is coming out from behind a relay at the bottom of the fuse block, here:
fuse5.jpg Photo by Annaleigh_123 | Photobucket

From there, they go into this box:
fuse6.jpg Photo by Annaleigh_123 | Photobucket


I believe it may be part of a keyless entry system. After searching over and over for the data connector, we assumed that perhaps the connector with the 2 led’s might be some kind of adaptor for a code reader and so we jumped out the last two pins like you would on a data connector. Turned the ignition on and the dash light up like normal but the service engine soon light just stayed on (no flashes). Next we attempted to start the van and when we turned the ignition switch to crank, we heard a pop under the dash and no attempt to crank. Pulled the jumper wire out of the connector and it was very warm as well as a slight smell.
Now the van will not crank. We could find no blown fuses so far and when you turn the ignition switch on, everything lights up on the dash like it should but just no crank when you turn the key to crank. Everything else on the van seems to be working fine so far.

I think we are going to have to take the dash apart to get to the rest of the wires to see what all the added wires are spliced into. It is my understanding that there should be no relay in the crank circuit unless an alarm has been installed that stops you from cranking the van. I don’t have a diagram for the ignition and starter circuits but if I understand from searching on the web, there should be a wire from the ignition switch going to the neutral safety switch and then straight to the starter solenoid. Thinking the next step might be to turn the ignition switch to run and try to manually crank the van from underneath at the starter. If it starts and runs, that would mean there is an alarm relay in the circuit. If it cranks but doesn’t run, then there might be a relay in the ignition circuit.

What are your thoughts on this?
Called 4 alarm companies and they all said I would have to tow the van to them and then they would tell me if it was an alarm (hate to have to tow the van all over town)
Thanks Anna
If anyone has a 95 diagram, I would appreciate glancing at it.

canucklehead

I cannot remember for sure about the starter relay. My 02 express has one though.
If you jump the pin on the starter solenoid it should crank. I am with you on the ignition switch being interrupted.
If you have power locks try unlocking the locks before cranking. Some cheap immobilizers cylcle with the keyless entry.
If you burnt something though, you may have to find that first.....

Annaleigh

Thanks Canicklehead
Well I was able to do some checking today and it does have an immobilizer. I can see where the purple wire in the column harness has been cut and spliced but I have to drop the steering column to get to it.
Further checking and all but one fuses hav power… the one marked SIR-CRANK has no power on the fuse block, the fuse is good. So before I drop the column, I need to find out why the SIR-CRANK socket on the fuse block has no power to it.

Any ideas?

Am thinking since the Crank circuit is spliced in the steering column, why would they need to splice into the sir/crank circuit before power reaches the fuse?
SIR is the air bag circuit… and should not be interrupted ( I think)

Annaleigh

Ok, problem solved! Yah! There used to be an immobilizer. It was not all there to start with. The plug with the 2 LEDs on it, the rest of the system must have plugged into that connector, someone had disconnected it previously. The second pic of what I thought was a connector with heat shrink around it, was a relay left behind from who ever disconnected the system before, it had been rewired to stay closed. When I jumped out that connector with the LEDs on it, burnt the relay out. I see why they left the relay in. I did not drop the steering column, instead I pulled the instrument panel out and still could not access the spliced crank wire going in the column. Rather then drop the column, the person who disconnected the immobilizer rewired the relay which was accessible from under the dash.
That’s ok, I learned a lot about immobilizes, I learned a lot about the wiring on the van, and will never jump out another connector unless I know exactly what I am doing! I also needed to replace the instrument panel lights because 2 were blown! .

Now I can get back to the original plan. I have to get emissions and the check engine light is coming on after driving a few miles. It is only getting 10 miles per gallon. The temperature gauge only comes up to about 135f when driving. Am assuming the thermostat is stuck open and the temperature never lets the ECM kick into lean mode.
Thanks again for your help..