1998 VT V6 auto no start, no crank, nothing - Lots of detail inside

[Sobek]

When you turn the key to reds can your hear the fuel pump prime then cut out?

Hey lowandslow - didn't get a chance to do anything further with the car last night, got home far too late and was far too tired to work on it. I'm sorry but can you just clarify for me exactly what you mean when you say 'the reds'? As mentioned I'm a BMW guy mostly so I've never heard that term before, I assume you just mean when the key is turned over to position 1 and the dash lights come on.

If so, I don't believe it does. Where the car sits is VERY quiet, and while sitting in it literally the only sound to be heard is the faint click of the blower relay when I turn the key over to try and start the car. On my BMW the fuel pump only runs when you physically turn the key over to start the engine, does it actually prime beforehand on these Holdens when the key is only in position 1? Either way, at no point have I heard the fuel pump prime or run, but then again, if the engine isn't even cranking, it's not like no fuel is going to make a difference anyway...

Or does that just point towards a specific problem you're thinking about?

 

[dope505069]

Hey lowandslow - didn't get a chance to do anything further with the car last night, got home far too late and was far too tired to work on it. I'm sorry but can you just clarify for me exactly what you mean when you say 'the reds'? As mentioned I'm a BMW guy mostly so I've never heard that term before, I assume you just mean when the key is turned over to position 1 and the dash lights come on.

If so, I don't believe it does. Where the car sits is VERY quiet, and while sitting in it literally the only sound to be heard is the faint click of the blower relay when I turn the key over to try and start the car. On my BMW the fuel pump only runs when you physically turn the key over to start the engine, does it actually prime beforehand on these Holdens when the key is only in position 1? Either way, at no point have I heard the fuel pump prime or run, but then again, if the engine isn't even cranking, it's not like no fuel is going to make a difference anyway...

Or does that just point towards a specific problem you're thinking about?

Reds mean the same on every car. Its turning your ignition all the way without starting it. When doing this all your 'red' dash lights and/or warning lights come on.

When you turn the key to the 2nd position without starting it the fuel pump will prime on the commodore.

 

[lowandslow]

I'm just thinking if it's not getting a signal to prime the pump when it should then there is another clue as to where to start looking.
Do your best and get a decent scan tool plugged in to it and see what it says. (unless you have done this already and i've missed it)

 

[Sobek]

Alright, crikey... The weather's been a pain and mum's partner (who owns the car) was bitten by a snake last time he went out to try and work on it, so needless to say we got delayed. But I had a few hours free this morning so we both went out and tried to get to the bottom of this. I'll say straight up that I completely neglected to check for fuel pump priming noises, and I forgot to mention this to him as he was the only one going in the car to turn the key for me... Can easily check that later though.

Now, my memory is like a sieve today so bear with me. Imagine you're standing in front of the engine looking in at the relays. At the starter relay, on the underside we've got four wires - top is the fat purple/white going to the ignition switch, bottom is the fat red/white for constant 12v power, left is a thin grey wire (to the inhibitor switch) and the right was... blue and grey? Pretty sure that was it, not sure what that one is for, never get any kind of reading out of that one and no idea where it goes. Anyway, the constant 12v power is always there, and when we turn the key to start, the top purple/white wire goes live (we're using a light-up tester to check) so it would seem the ignition switch is doing its job. Next we moved over to the grey wire, which goes to the inhibitor switch. Whipped out the multimeter, disconnected the plug from the inhibitor switch and tested - we got 0.8ohms, so there's a solid connection from the relay down to the inhibitor switch through the wiring loom. Next we tested the inhibitor switch itself by hooking up the multimeter to the grey and blue/grey wire connectors on the inhibitor switch itself, and got the same 0.8ohms - seems like the inhibitor switch is working OK too.

So where does that leave us? Seems to me like the ECU is the most likely culprit. I see they're cheap and easy to replace, I found a matching CJKU V6 3.8L Auto on eBay for about $50, but I'm guessing it would need to be linked into the car by an auto electrician? Please, let me know if I've missed anything else... Thanks again guys!

 

[Sobek]

No thoughts anyone? Ready to purchase a new ECU and such now if you think that's the best course of action. Just want to be certain I'm not missing anything else important!

Cheers

 

[Tasmaniak]

Help me clarify this mate...
Red/White is a thick wire and has constant output at 12V? If you look under the relay does this line up with Pin 30 on the relay? (relay will be marked)
Purple white is a thick wire that goes live when cranking and will line up with either pin 85 or pin 86 on the relay correct?
The grey wire shows ground when in neutral or park? To test this, use your test light and put the alligator clip on the positive terminal, then put the probe into the grey wires terminal. When in park or neutral the light should light up... if it doesn't, that's your culprit. Doesn't matter if the wire has a solid connection between the inhibitor switch and the relay, if there is nothing flowing along it... you've got nothing.

 

[dirty hands]

the ecu is just a plug in plug out

you can do this yourself

 

[Sobek]

Help me clarify this mate...
Red/White is a thick wire and has constant output at 12V? If you look under the relay does this line up with Pin 30 on the relay? (relay will be marked) Purple white is a thick wire that goes live when cranking and will line up with either pin 85 or pin 86 on the relay correct?
The grey wire shows ground when in neutral or park? To test this, use your test light and put the alligator clip on the positive terminal, then put the probe into the grey wires terminal. When in park or neutral the light should light up... if it doesn't, that's your culprit. Doesn't matter if the wire has a solid connection between the inhibitor switch and the relay, if there is nothing flowing along it... you've got nothing.

Correct on all counts - thick red + white wire is the constant 12v and is in pin 30. Thick purple + white wire is in pin 85 and only goes live when the ignition is turned over to crank. To be honest though, I'm not sure if we tested the grey ground wire by connecting with the positive terminal, strange as that sounds. I think we just went straight to testing its continuity with the inhibitor switch. I'll check on this shortly for you. Let's say I get no light from testing the grey wire with the positive terminal, where do you think the fault would lie in that case? Bear in mind we've replaced the starter relay with a good working one and that's made no difference.

the ecu is just a plug in plug out

you can do this yourself

Yep that's no problem, got the old one exposed at the moment while we work out what to do. Problem is I keep reading in every thread I find that from the VT and on, it has to be synced to the BCM with a diagnostic tool (a tech2 I believe) or the security system will just lock everything down. Are you saying that's not actually true?

 

[lowandslow]

You will neEd the New ecu matched to your cars bcm otherwise it won't work. Unless the new ecu has VATS disabled.

 

[Sobek]

Help me clarify this mate...
The grey wire shows ground when in neutral or park? To test this, use your test light and put the alligator clip on the positive terminal, then put the probe into the grey wires terminal. When in park or neutral the light should light up... if it doesn't, that's your culprit. Doesn't matter if the wire has a solid connection between the inhibitor switch and the relay, if there is nothing flowing along it... you've got nothing.

OK, delays again sorry, dad's had a suspected minor heart attack and we've all had to go to hospital with him for a bit... Can't catch a break can we. Anyway, pin 30 on the relay is the grey inhibitor switch wire on this car. I did as you said and hooked the tester up between the positive terminal and grey wire's terminal, and there was nothing, no light. Tried every combination of positive with it and never got any response. What does that indicate is at fault exactly? Also, no sounds of fuel pump priming when you hold the key over.

You will neEd the New ecu matched to your cars bcm otherwise it won't work. Unless the new ecu has VATS disabled.

Cheers, I figured that was the case!