1989GTA

Thats what I did. I tied X1-9 into transmission wire from pin 6.

rascalking

Thanks man.

1989GTA

One more thing. On my wiring harness both wires went to the old fuse block which was only partially there. So I just added the wire and brought it on to the brake light switch.

rascalking

Ok. But the resistor is absolutely necessary, right? I saw a post on hptuners forum where the guy was having trans problems and he was just grabbing the 12 volts right from the brake light switch, no resistor.

1989GTA

Hmmmm, I can't find my schematic at the moment. However the resistor simulates the brake light bulb when the pedal is released. I would look at the car but it is in the shop getting the A/C charged for the first time and a 1/2" spacer under the front coil springs to raise the front 1". By the way I have no problems with my transmission shifting.

With the dual switch when the brake is applied there is twelve volts applied to the blue/white wires. When the brakes are off there is a ground through the resistor to ground simulating the bulb. From my GM schematics, there is a built in resistor in the ECM. Same with the TCM. So they can take a straight shot of 12V from an ignition on source. Fuse 44 on my schematic.

rascalking

That helps a lot, thanks. If you don't mind, I have a couple of other questions I've been struggling to find answers to, and since you have the same setup I thought you would know. As far as the cooling fan and fuel pump wires coming from the E38, do they have enough voltage to trigger regular 12 volt relays? I don't have access to all of the wiring schematics and I want to wire it correct the first time.

1989GTA

Regarding the fan relays. The ECM provides the ground circuit for the relay coil. It does not provide the 12 volts. The other side of the relay coil goes to a 12V ignition voltage source. Same with the fuel pump. Right or wrong with my car anytime the ignition is on the fuel pump runs. I do have an emergency shut off on the rear of the car.

On my car I have A/C. I have provided a relay so that anytime the A/C is on the high speed fan also comes on. What this A/C relay does is provide a 2nd ground for the high speed fan relay. EMC X1-17 provides the other ground for normal circumstances.

rascalking

Ok, got it. That makes more sense. I appreciate the help.

rascalking

So is the power train control relay from pin X1-59 the same? It provides a ground for the trigger?

1989GTA

Yes it is. In this case the power to the power train relay coil comes from B+ or the battery. Then the ECM through pin X1-59 provides the ground to the relay coil when it is ready and will turn it on.

rascalking

Thanks again. I think I have everything figured out for the engine and trans. Now on to the BCM and cluster wiring...if anyone has the BCM pinout for an 07/08 Escalade, I could really use it to finish this up.

ShawnQ

GTA,

Is the Powertrain Control Relay even needed?

Everything I have read has people deleting this circuit and just tying all of the ignition wires into a key-on 12v+ source.

I'm just finishing up my harness as well...and I removed this pin (didn't cut anything, just unpinned it).

Thanks.

1989GTA

I read somewhere that you might get a code or a problem with the ECM if that was done. Basically the ECM is looking for power from one source first than the 2nd source shortly there after. I just went along with the way the factory did it so there would be no problems.

If others have done it differently with no problems then I don't know.

ShawnQ

Thanks for the info...that makes sense. My assumption is that when people remove it, they also remove the reference from the tune on the ecm.

1989GTA

That could be true, I just don't know. To be safe I just followed along as to what the factory did. Basically I just followed the GM schematics regarding the wiring as I modified the factory wiring harness. I figured I would have enough problems to sort out without adding any potential problems.