VR Engine Light from VT PCM

[wamboin23]

Hi There,

I have a 1994 VR Commodore Acclaim, running a 1998 VT Supercharged V6 Engine. My problem is getting the check engine light to work. If I can work out how it is triggered in the VT (read: need the code that is been transmitted on the serial connection), then I might be able to write a program to search for this engine light 'trigger', then turn it on.

OR, if one of the USB adaptors that are in the For Sale section on this site, would allow me to do what I want to do above (read whats going on in the computer), plus more, this might be a better option.

Looking forward to your ideas,

Brendan

[Holden202T]

i'm not sure what your saying ....

if you want to get the light on so you can see if your light is working then jumper the aldl port to get the codes out ... it should then flash.....

[delcowizzid]

nah i think the whole dash is done via can bus comms or similar

[wamboin23]

nah i think the whole dash is done via can bus comms or similar

correct. engine light, temp gauge, PRND321 indicators etc etc. speedo, tacho are 'analogue' connections so speak...

[delcowizzid]

easiest way would be to roll back to a VS ecu with the supercharger tune i think theres only 2-4 wires different on the ecu plugs would allow a stock VR dash to work fine

[wamboin23]

easiest way would be to roll back to a VS ecu with the supercharger tune i think theres only 2-4 wires different on the ecu plugs would allow a stock VR dash to work fine

and the memcal from my vt ecu, won't go into vs ecu will it...

[delcowizzid]

no but it would be fine running on a VS ecu and VS supercharged memcal im sure .just need to get an RF ecu or the supercharger ecu cause they are fully populated with boost control and slow fast fuel pump circuits

[wamboin23]

be easier to use vt dash circuit board and run wires out to vr dash??? only just spent the money getting vats turned off and hsv tune.

[Doctor Bob]

the major difference is the vr PCM is the bus master
in the VT the BCM is the busmaster & the PCM wont do diags until it gets the request from the BCM.

nothing to do with the dash.

Rob

[Biggsy]

Actually, the check engine light has everything to do with the dash. You are correct about the BCM being the busmaster in a VT though. The VT check engine light is turned on by the instrument cluster after receiving the instruction to do so via the serial data line. You need a SDI box to act as the "dash" and get it to turn a light on when it sees the check engine light command on the data line. There are companies however, that are able to reprogram the code in the VT memcal to create a check engine light output directly from the PCM, they can also get the PCM to operate low speed thermo too (BCM normally has control of low speed fan in a VT).

The last conversion of a VT motor into earlier model car I was involved with, we hacked a BCM and Dash and mounted them into a box.

Dave.