66 replies to this topic

[siztenboots]

correct same wire

[NDT]

it would crank, just wouldn't start

 

very helpful - thanks

[NDT]

Zoobeef, sizetenboots - very helpful stuff. thanks. Going to try bridging the immobiliser terminals and see whether we get some comms.

[vocky]

you cannot 'bridge' the vauxhall immobiliser system, all you will do is possibly cause damage

 

It is a single wire from the immobiliser to the ecu which gives the required handshake to make the engine run (X31 - pin 2)

[JohnTurbo]

When you say its earthed have you tried a jump lead from thr casing to the engine block? Mine looked earthed but was too corroded to contact. All other symptoms identical.

[NDT]

When you say its earthed have you tried a jump lead from thr casing to the engine block? Mine looked earthed but was too corroded to contact. All other symptoms identical.

 

I checked continuity from the earth wire to the block and from the ECU casing to the block.

Both were fine.

 

[NDT]

you cannot 'bridge' the vauxhall immobiliser system, all you will do is possibly cause damage

 

It is a single wire from the immobiliser to the ecu which gives the required handshake to make the engine run (X31 - pin 2)

 

thanks.

This came from a Vauxhall diagnostic guide - put a fused jumper wire between 6 and 7 on the immobiliser connector and see whether comms get established.  

[Zoobeef]

 

you cannot 'bridge' the vauxhall immobiliser system, all you will do is possibly cause damage

 

It is a single wire from the immobiliser to the ecu which gives the required handshake to make the engine run (X31 - pin 2)

 

thanks.

This came from a Vauxhall diagnostic guide - put a fused jumper wire between 6 and 7 on the immobiliser connector and see whether comms get established.  

 

 

 

Soooo, whos testing that I don't want my immobiliser.

[NDT]

 

 

you cannot 'bridge' the vauxhall immobiliser system, all you will do is possibly cause damage

 

It is a single wire from the immobiliser to the ecu which gives the required handshake to make the engine run (X31 - pin 2)

 

thanks.

This came from a Vauxhall diagnostic guide - put a fused jumper wire between 6 and 7 on the immobiliser connector and see whether comms get established.  

 

 

 

Soooo, whos testing that I don't want my immobiliser.

 

 

Only bridging on the loom side connector, not the immobiliser itself.

Anyway, we'll see if it helps. Or not.

 

[Zoobeef]

Ahh yes I see now!

[NDT]

might be getting somewhere now.

Bridged 6 and 7 on the immobiliser plug so the ECU has a clear path to the diagnostic plug. No joy.

 

However while checking the pins I found that pins 4, 5 and 6 on the immobiliser plug appear to be joined.

Which is probably not helpful as 4 goes to the battery negative, 5 is power from fuse 7 and 6 goes to the diagnostic plug.

[NDT]

might be getting somewhere now.

Bridged 6 and 7 on the immobiliser plug so the ECU has a clear path to the diagnostic plug. No joy.

 

However while checking the pins I found that pins 4, 5 and 6 on the immobiliser plug appear to be joined.

Which is probably not helpful as 4 goes to the battery negative, 5 is power from fuse 7 and 6 goes to the diagnostic plug.

 

this was a red herring - obviously my crappy test kit.  

[NDT]

SOLVED - turned out to be a broken wire near the X3 connector in the loom of doom behind the coolant expansion tank.

My biggest mistake was ignoring a voltage drop on one of the power wires at the SCU connector - I assumed 0.5v different to everything else was ok - it's not!

[jayworth2]

Did you check Zoobeef's suggestion of grounding the solinoid part of the fuel pump relay to activate the fuel pump...if the pump then runs its probably be an ECU problem....and I could give you the whole saga of what happened in my case!

 

I have a similar problem If I put the earth pin on the fuel pump relay to another known good earth the fuel pump will prime & engine will start. Hoping it's only going to be a bad earth somewhere. How will I know if I 'am going to have ECU problems that you had?

[siztenboots]

 

Did you check Zoobeef's suggestion of grounding the solinoid part of the fuel pump relay to activate the fuel pump...if the pump then runs its probably be an ECU problem....and I could give you the whole saga of what happened in my case!

 

I have a similar problem If I put the earth pin on the fuel pump relay to another known good earth the fuel pump will prime & engine will start. Hoping it's only going to be a bad earth somewhere. How will I know if I 'am going to have ECU problems that you had?

 

 

check continuity of the inertia switch ,

 

Its inline of the two relays , its only this which breaks the supply to the relay for fuel pump and injectors.

 

so although the relay maybe be fine , the inertia switch could be open circuit .

[jayworth2]

So if i'am grounding pin 85 of the fuel pump relay i'am bypassing fuel cut off switch?  If I use the engine block as earth I get power at all relays but if I use the white / purple wire at fuel pump relay pin 85 as an earth I only get very small readings on all relays. 

[siztenboots]

yes 85 , when put to ground will energise the relay , but the 12v supply that it switches comes from the thick 2mm white-violet wire . This wire is from the FCO switch.

 

what is the voltage like on pin 86 (Red-Blue) on the relay as this is also the common feed to the FCO switch?

[jayworth2]

On pin 86 of the fuel pump relay with the multimeter grounded to the engine block i get 12V

[siztenboots]

also  , lift off the black plastic loom cover by the fuel rail 

 

check the red-blue wire on any of the injector plugs for 12v , as this is also common to the fuel pump supply , and this is the output of that relay.

[jayworth2]

No 12V at the injectors from the red / blue wire. Found the white / violet connection at the blue plug at the loom of doom & if this is +12V i'am not getting any voltage at it. Checked fuel cut off switch which is closed circuit as it should be & goes open circuit with a bang on it. Really stuck now as to what to check next?