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Another BCM/ECU question

2O4TS

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Hi all. So I've fitted a different BCM to my VT. Car was a mid level to which I've fitted a high level BCM and replaced all the body wiring, front to back from a WH Statesman. Good fun.

I know (thanks to this forum) I have to get the BCM and ECU matched. Seems surprisingly (to me based on what I've read) difficult for the local mobile auto sparkys here on the Gold Coast. One asked me "Why would you do that"? Called three before I found one who believed matching the pair could be done yet of course I know from reading here it's been done many times.

Anyway my question is, should the car turn over before the ECU and BCM are matched? I've read several threads where posters have mentioned after either a BCM or ECU swap that their car quote "won't start" but should it turn over? I've had an issue with the key head before where the car would turn over but wouldn't start. Should it be the same now? I just want to make sure everything is as it should be before the sparky starts gouging me.

Thanks for any help.
 

Brett_jjj

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If the keyfob matches the BCM, but the BCM is not linked to the ECU, then the engine should crank over, but not start, or if it does start, it should stall after 2 seconds. If the keyhead (fob) does not match the BCM, then the car should not even attempt to crank.
 

2O4TS

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Many thanks Brett_jjj. Seems I may have more issues then unfortunately. I don't know but I forgot to swab fobs for the replacement BCM and got nothing but dash lights as you mention, but after slapping myself in the head and swapping my original key onto the fob supplied with the BCM, it still won't crank. In fact other than cluster lights when turned to "on" I have nothing at all. No headlights, no indicators, nothing. I still have some wiring of external lights to do, passenger headlights/indicators, ambient temp sensor (which I have to extend the wiring on so assume the WH has it mounted in a different place or something) horns, fog lights (different plugs to the VT's as WH has indicator fog light assembly so will need different plugs/soldering) and all the rear lights and rear demister to sort out but everything else is done. Most of it (other than what I've mentioned) has been 'plug and play' except the rear light will be an issue. But this not cranking thing has me worried now. Could having attempted to crank with the wrong key fob caused some issue which will now need to be cleared too I wonder? If not, I'm stumped as to why it won't crank.
 

accentstencil

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The ambient temp sensor is located at the front of the condenser on the driver's side on WH models.
As far as it not cranking, it would have nothing to do with the key fob or the BCM not being linked to the ECU. Have you checked all the fuses and fusible links?
 

2O4TS

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The ambient temp sensor is located at the front of the condenser on the driver's side on WH models.
As far as it not cranking, it would have nothing to do with the key fob or the BCM not being linked to the ECU. Have you checked all the fuses and fusible links?

Cheers. Yeah that's where the temp sensor is normally located on the VT too. I pulled the sensor from a 'wreck' myself so I'm stuffed if I know why I'm so stuck for wire length. The plug for the ATS is identical on the WH loom and VT loom but there's just not enough length in the wire. I'll explain in more detail. The loom branch that has the ATS plug also has a thermo fan plug on the passenger side. You know there's two plugs just underneath the Auto Trans Fluid reservoir (as well as one other plug I think without running back outside and looking right now) and there's just not quite enough length to reach the ATS once I plug in the thermo fan plug on the passenger side to also plug in the ATS.

Anyway that's a relatively minor issue for now. IRT the 'non-cranking issue, thanks for the advice. I can only think maybe a relay either under the dash or bonnet. A major disadvantage right now is that I don't have a guide to what goes where in regards to both those fuse/relay boxes. I didn't pull the loom, it came with a Climate HVAC without any fuses or relays. I've had it a couple of years with the idea that when my heater core died I'd do the climate control conversion. Removing and replacing the HVAC was no big deal really but the wiring.... You know how it is. I figured I'd be 'ahem'... clever and do a whole loom swap and upgrade everything I could to Statesman specs. Anyway what I don't have is a fuse box lid with a diagram of the fuse/relay locations. I do have a full compliment of fuses and relays in both ATM except they are the VT ones so I may well be a relay short and/or not have a fuse somewhere where I need one so I'll have to track down a diagram of what goes where in the fuse/relay panel & box. Nothing has fried so no issues there fortunately. There's a guy lives down my street with a WH so I'm about to head down and politely ask if I can snap a couple pics of his.

Thanks heaps for your advice. Most appreciated. I will update if I have any other related questions and/or when it's sorted.
 

2O4TS

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Well my neighbours with WH's have sold them unfortunately and I've checked every fuse and fusible link I can find without luck dammit. Was hoping I'd find something there but no go. Have pulled relays from a running VT and tried with those, still no good. The BCM makes an audible click a second or two after turning the ignition to on followed by a click from the ECU. The BCM also clicks after opening the drivers door. Further clicking ensues from the engine but I can't specifically locate that easily. Injectors maybe? I have all the reds on the cluster and the climate display is active and air con/heater fans blowing but still no ignition, dash illumination or lights. Have called an auto sparky but shuddering as to what he's gonna charge me as I'm yet to speak to one that shows any sign of confidence in their ability.

Have asked this question elsewhere but if any V6 WH owners on here could post or send me a pic of their fuse/relay boxes with the layout diagrams I'd really appreciate it. Something's not right somewhere and I desperately wanna get this thing running again. Cheers in advance.

Edit: Have discovered I also have power to what I believe to be the mobile phone loom branch and have the centre interior light working, albeit a little dull. The door actuators also work with the key remote. I have 12.3 volts at the battery.
 
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accentstencil

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!2.3 volts could be a little low, have you tried another battery?
 

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you have connected the auto inhibit switch and checked the trans is in nuetral/park
1997 relay box has starter relay rear right as viewed from drivers position
1998-1999 relay box has starter relay rear left as viewed from drivers position
2000-2002 relay box has starter relay 5 back left as viewed from drivers position
 

2O4TS

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you have connected the auto inhibit switch and checked the trans is in nuetral/park
1997 relay box has starter relay rear right as viewed from drivers position
1998-1999 relay box has starter relay rear left as viewed from drivers position
2000-2002 relay box has starter relay 5 back left as viewed from drivers position

Yes to the first one. That was one of the earlier things I checked because it is definitely symptomatic of that. I've also noticed the cluster warning lights don't dim at all when I turn the key.

Your tips on the starter relay positioning are most appreciated. IDK the vintage of the loom unfortunately but I can re-try following your suggestions. I've already done a bit of relay swapping round just in case with no luck. It is unimportant to me at the moment if anything non-essential to get it to crank is left out. Wipers, headlights etc, don't care. I'll cross that bridge later. Just want the bloody thing to show some sign of life. Again, thanks for the tips.
 

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if you can, post a pic of the fusebox so we can identify it better
do you have access to a multimeter and a bit of an idea how to use one
 
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