66 replies to this topic

[NDT]

does anyone have a diagram of the ECU connector pin numbers for motronic please?

[NDT]

Actually what would be really useful is which of the two ECU connectors is which!

thanks!

[Zoobeef]

Pin 18 of plug X31 of the ECU is the power from fuse 8. Is a Violet wire.

 

Check power at the fuse, check power one of the plugs behind the header tank (pin 13 on plug x3) and then at the ECU. Should be Violet the whole way.

[NDT]

Thanks - really helpful. Which one of the two ECU connectors is X31 - closer to the car centreline or closer to the left hand side?

[Zoobeef]

I'm not sure. You may just have to see which ones got the violet wire in the correct slot.

[NDT]

thanks - when I get back on it I'll post the results

[siztenboots]

pictures of the two ecu plugs,

 

tvxr ecu plugs

 

Atmospheric barometer sensor plug , x31 left ,  x32 right , in situ . Earth wire hiding behind.

 

Security bolt and bracket drilling out

 

The 3rd ecu is just my spare with the K6X label

 

 

[NDT]

pictures of the two ecu plugs,

 

tvxr ecu plugs

 

Atmospheric barometer sensor plug , x31 left ,  x32 right , in situ . Earth wire hiding behind.

 

Security bolt and bracket drilling out

 

The 3rd ecu is just my spare with the K6X label

 

You're an absolute star - thanks!

Would be good to talk to you about a remap in the new year too.

[NDT]

Bad news. ECU loom has power to both the pins that should have. Next stop ECU?

[Nev]

Have you done a simple test to see if the plugs are sparking up? Do that next, as it's a simple test and fundamental to ignition.

 

Edited by Nev, 09 December 2017 - 06:57 PM.

[kipper]

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!

[NDT]

Thanks guys.

Haven't checked those as my friendly local Vauxhall specialist (Griffin Autos) stuck a Tech2 on it and couldn't get any response from the ECU.

So given that the ECU is powered and earthed I suppose that's the next thing to look at.

[NDT]

What I've found so far...

ECU has power

ECU has ground

K18 ECU relay has power

K16 fuel pump relay DOESN'T have power - even when K18 is bridged (K16 is fed from K18 via the fuel cutoff)

fuel cut off works ok (have taken it off and tested it)

 

So the finger of suspicion points at the wiring between K18 and the FCO and between the FCO and K16.

One red herring though - a code reader doesn't detect the ECU (leading me to think that the ECU was fried) but replacing it with a good ECU made no difference - code reader still couldn't detect it.

 

Happy for any suggestions!

 

[Zoobeef]

Have you got power at terminal 87 on relay K18? But none at terminal 30 of relay K16? It also goes through a 20A fuse in the boot before the cut off switch so see if you have power there too. You can joint those 2 relay terminals direct to bypass the cutoff to test it too.

[NDT]

Have you got power at terminal 87 on relay K18? But none at terminal 30 of relay K16? It also goes through a 20A fuse in the boot before the cut off switch so see if you have power there too. You can joint those 2 relay terminals direct to bypass the cutoff to test it too.

 

exactly right - when I bypass K18 (bridge 30 to 87) I still don't have anything at 30 of K16.

I will check power at the 20A fuse - thanks

[NDT]

I obviously wasn't bridging K18 properly before... just done it again and I've got power at K16.

Then when I bridge K16 I can hear the fuel pump running.

And got power at both the 20A fuses.

It all points to a duff ECU.

[smiley]

Its a bit of a wild guess, but it has happened that an ecu lost the handshake with the fhiomin thevkey. Have you tried your spare key?

[NDT]

Its a bit of a wild guess, but it has happened that an ecu lost the handshake with the fhiomin thevkey. Have you tried your spare key?

 

have tried both keys.

Wouldn't an issue with keys / immobiliser stop it from cranking?  

[chris_uk]

it would crank, just wouldn't start

[Zoobeef]

From what I can see the Diagnostic socket goes through the immobiliser to talk to the ECU. Unless I've missed a wire. Something wrong with the immobiliser or communication between the immobiliser and ECU?