No power at all, continuity from engine to battery (+ve)

[nexx]

Hey all, looking for some advice on a VZ SV6 as I'm unfamiliar with commodores and I hear a lot about BCM issues etc.
The situation is, after degreasing the engine bay fusebox (filled with red dust) and cleaning relay terminals I have absolutely no power to the car at all, no central locking, no lights, no ignition surround light, no dash cluster. Dead in the water. I've run through all the basics that I could think of, so I'm looking for some advice before I hand it over to an Auto Electrician. Is there something obvious that I'm missing? Here's what I've checked so far:

Continuity
----------
Intake manifold/block -> chassis
battery (-ve) -> chassis
Intake manifold/block -> battery (-ve)
Intake manifold/block -> battery (+ve) -> short!?

Relays
------
Ignition (under dash) -> audible click from coil
Engine Control Relay -> audible click from coil
Swapped a few relays around to try and eliminate them.

All fuses have continuity (not blown)
Fusible links look okay
All relay pins in the fusebox have continuity to battery(+ve), (-ve) seemed hit and miss -> Bad ground/short from degreaser?
Alternator charge wire has continuity to battery (-ve), possibly through short elsewhere as removing charge wire had no effect on problem and block still had continuity to battery (+ve)

Cheers for any help.

 

[Nut Kracker]

What did you use exactly to clean the fuse/relay box?
Did you disconnect the battery first?
Does the car start?

It's not a good idea to squirt liquid around electrical components.
Just a damp rag would be best.


Check all earth's to the body.
Thoroughly check all fuses, relays and fusible links with a multi meter.
Looks can be deceiving.
Check BCM fuse inside the car.


Try this.....
Disconnect the battery.
Unscrew the fuse/relay box from the guard.
Lift up the fuse/relay box and check for any burn wires in the loom, especially the main earth wire from the fuse/relay box, as described below.

I think on the VZ (on the VT anyway), there is an earth wire (black, I think) that runs from the fuse/relay box to the body of the car. It connects to the body just under the
right hand side headlight assembly.
This earth is connected to quite a few components in the fuse box and is often over looked as a problem.
Check that this wire is not burnt out.

 

[nexx]

Stupidly enough I thought I'd disconnected the battery and only realised after that I hadn't. It was cleaned with a liberal amount of degreaser. Main earth seemed fine, nothing blown or burnt. It's very odd. Is the BCM fuse in the fuse panel under the steering wheel? If so all fuses in there are fine. Got an auto sparkie coming to look at it today. I'll let you know the outcome.

 

[rory]

Better off using something like this for electricals with dirt in them as it will evaporate quickly and will not cause shorts, just a point for next time. Although you might be able to blow out the degreaser with it even now.
Cleaning solvents- CO Contact Cleaner
Good luck with the auto electrician today and let us know what he finds.

 

[nexx]

Turned out to be dodgy battery terminals, not sure exactly why it wouldn't work no matter how much I played with it, yet seemed to show continuity. Explains why a second battery didn't fix it.

 

[Tasmaniak]

depends on how you measure continuity.

 

[Nut Kracker]

Certainly not with a test light.

 

[nexx]

depends on how you measure continuity.

I had continuity, and the resistance was reasonably low, I didn't play with it though, moving it must have made resistance go through the roof.

 

[mtw002]

When you tested for continuity was the battery disconnected? as the battery has an internal resistance and can give false readings.
when doing the continuity test You shouldn't be able to get a low impedance from chassis, or any metal part of the car to the +Ve terminal on the battery leads, that indicated a short cct, not a high resistance join, that will just cause mass voltage drop and cause nothing to work.

When you were testing the fusebox was it still soaked in the degreaser? that would cause your short cct. (may not have been dry across any 2 terminals)


Either way use a blower to clean out a fuse box, you dont want any liquid there, alive or dead, as it will just aid in corrosion and cause problems.

incase you didnt pick it, im a sparky haha.

 

[Tasmaniak]

ooOOoo he is a sparky! He gots da volts maaaaan, he must be having the volts cos he is da sparky with the volts maaaaan.

ya.... I gots da volts to maaaaan.

you gots da volts maaaan?

I got volts.....