VZ E38 Reverse lockout

[Shelby]

Hi,

I have a VZ Commodore set up in a AC Cobra and cannot get the reverse lockout to work.

Have logged the reverse lockout and it is changing status in the ECU, but the ECU output on the pin is a constant 0.5V. (Log attached)21298

It should ground out over 5km/h. That part of the harness is stock VZ commodore and is output is on the X2 connector, pin 11.

Tuner reckons is should be working, however, every other problem we have had has been on his end, and not a wiring issue so I have low confidence.

Any ideas - is there an alternate pin on the E38 that might be outputting the reverse lockout signal.

Thanks.

[joecar]

Are there any other enables besides vehicle speed...?

[Shelby]

I do not have a clutch position switch but have hooked up a temporary 12v to what would be the right pin if I did, but it did not make any difference. Not sure what parameters can be changed in Efilive as I dont have access to the tune. About to give up on this one and just hook up the reverse lockout to the brake pedal as I know a few others have done. Just figured that would result in greater wear on the reverse solenoid then I would have otherwise.

[GMPX]

X2 connector, pin 11 is the correct output. One side of the solenoid goes to 12V, the other side to the ECM pin, the ECM will switch it to 0V when on, the ECM pin will sit at 12V when off.
To test the wiring side the tuner can open up the scantool in V7 and manually control the Reverse lockout solenoid, but just check the wiring on the non ECM side of the solenoid is not going to GND, it needs to be like this.

Correct:
ECM X2,11 -----> Solenoid -----> +12V

Wrong:
ECM X2,11 -----> Solenoid -----> GND

Cheers,
Ross

[Shelby]

Thanks Ross, it is absolutely wired right and have double checked it many times. I did start with a stock VZ harness and the x2 connector and associated wiring was pretty much unchanged. I actually currently have the ecu side of the solenoid wired to a little switch on the consul with ground on the other side in order to switch it manually at present. Really has me stumped but at least there is an alternative, just not ideal.

Cheers

[joecar]

Check that you have all the ECM grounds connected.

[Shelby]

I thought that could be it but I can only see one ground in my diagrams X1-73 which is hooked up fine. Are there any others i have missed?

[joecar]

I thought there were more grounds than that... I'll see if I can find some factory wiring diagrams.

[GMPX]

I thought that could be it but I can only see one ground in my diagrams X1-73 which is hooked up fine. Are there any others i have missed?
That is the main ground point and as far as I know the other ground pins on the ECM are all tied together anyway.

However you said "but the ECU output on the pin is a constant 0.5V", with the Reverse Solenoid off that should be at 12V, not 0V. It would be at 0V if the solenoid was grounded on the non ECM side and not connected to 12V.
As I also suggested, get the tuner to test the solenoid output using the DVT controls in the scantool.