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

[Sobek]

Hey guys,

This is my first post here obviously... I don't really have anything to do with Holdens, I'm more of a BMW guy, but my mum's partner has a 1998 VT which has an odd and sudden no-start issue. I've asked about this on another forum I use, but it's not a Holden or Automotive-specific forum so I wanted to come here where all the proper knowledgeable folk reside. I'll copy what I posted elsewhere below, and perhaps you can offer some insight... Excuse the long post, I just want to be thorough about what we've checked out so far;

Turning the key on to start the car turns off the red security light (immobiliser seems to be shutting off right?). When you turn the key to start the car, the only noise is a click from the blower relay which is normal – absolutely no other noises, no action from the starter, nothing. We checked the starter with a light-up power tester and power isn't being sent to it, so we moved up to the starter relay and checked that instead. The starter relay itself is working fine, and with the tester we can see that power is available to the relay. We tried swapping the relay and it made no difference, but we were able to engage the starter and get the engine cranking just fine by removing the starter relay and jumping the pins. The engine wouldn't start though as I imagine without the key turned over the immobiliser is stopping it from injecting fuel?

All other fuses and relays are in fine shape, we checked absolutely all of them for the hell of it. Tried turning the key to the run position and leaving it for over an hour to see if we could bypass the immobiliser but that did nothing at all. I tried shorting pins 5 and 6 on the diagnostic plug and turning the key as per online guides, but it never flashes any codes. Car has plenty of fuel, battery is good (we have spare good batteries and nothing makes a difference). All interior lights and controls work, including trip computer. Both keys remotely lock and unlock the car, and the slip rings make perfect contact so they're not the issue. We've removed the battery and turned the key for an hour or so to completely drain and 'reset' everything, but that made no difference, and we tried running it through the gears to ensure the neutral safety lockout wasn't active, but no go.

What do you guys think? Could it be the ignition switch or bad computer module? Not sure if just removing and re-seating the ECU might help if there's a bad connection or something. I can see that VT auto V6 ECU's are cheap as chips on eBay, but am I right in believing I would need to have the module linked with the BCM by someone with a Tech2 tool?

Appreciate any help you guys can offer, cheers!

 

[dope505069]

I wouldn't rush out and go buy an ECU. Someone here should be able to help you.

 

[dirty hands]

need a diagnostic tool for fault codes

 

[ballbaggins]

inhibitor switch maybe do the reds come on? try moving it from park to neutral a few times... worth a try

 

[Tasmaniak]

neutral safety switch or ignition barrel.

Out of curisosity, have you tried starting the car in Neutral?

 

[lout]

neutral safety switch or ignition barrel.

Out of curisosity, have you tried starting the car in Neutral?

what he said

 

[Tasmaniak]

Go back to the starter relay. Ignore the two pins that you jumped earlier and focus on the other two... the coil. When you hold the key in the crank position, one should show a positive signal and the other pin should be a ground connection.

No 12V+ typically means the ignition barrel (purple wire at relay and ignition barrel)
No ground signal means either Neutral safety switch or PCM.... Order of flow is that the PCM sends a ground signal to the Neutral safety switch, if the switch is closed (park or neutral) it allows the negative signal to flow directly to the start relay.

Have a look at the diagram below. The one highlighted in yellow is the likely culprit.. mind you, it could also be the wire on the right of it.

 

[delcowizzid]

turn key to the on position is the check engine light glowing if not the ecu doesnt have power

 

[Sobek]

Hey guys, thanks for the replies. As mentioned in my original post, we have tried running the shifter through all the gears (and we did try starting in P/N/D but no go). Ballbaggins - when you say 'the reds' do you mean the various dash lights? If so, yes, they all come on as expected if you were starting the car normally. Also, the check engine light does come on for a short time before turning off, as per normal too.

Tasmaniak, thank you that's extremely helpful. I remember we checked each of the pins for continuity and ground, but in all honesty I can't remember what each one showed. When I get home this evening we'll get a look at that again and see if we can't narrow it down some more. I'm hoping it's something simple... The car was basically perfect before all this - it was parked in its usual spot and left for a couple of days (normal) then suddenly it's doing this. We thought perhaps a rat came along and chewed something, but on visual inspection we can't find a single thing that's even nibbled on.

It's a mystery but I'm sure we'll solve it, will update our findings regarding the relay tonight

 

[lowandslow]

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