Limp mode/ No throttle response

[moggie93]

Hi guys, looking for a bit of help.
My 53 plate avf avant has went into limp mode. I was travelling on the motorway,when the glow plug light and the traction control light came on.
The throttle pedal was non responsive so I turned ignition off and back on and all was fine for about 10-15 seconds then the same happened.
I have tried to see if there are any fault codes but neither of the 2 code readers I tried would connect with the ECU.
Any help would be greatly appreciated.

 

[pauldazzle]

Could be a number of things so you need to get diagnostics to work. You could try checking the ECU fuses in the end of the dash as one of them is for the diagnostic port I think.

 

[pauldazzle]

IIRC a broken brake light switch can cause your symptoms. Also check the Plenum chamber under the Battery & Servo for rain water as it's very common for the drain plugs to get blocked which can cause all sorts of problems.

 

[moggie93]

Thanks for the replies guys, plenum chamber is dry although it was raining previous to this happening.
Brake lights are working ok.
I'll check fuses in the morning.
Strange thing is using the code readers I can connect to the abs and airbag ecu's but not the engine ecu.
Thanks again.

 

[Broken Byzan]

engine control relay dead, that would explain both faults

 

[moggie93]

Thanks Broken Byzan.Where is the engine control relay?

 

[pauldazzle]

i think it's under the ECU box.

 

[moggie93]

Thanks Pauldazzle, Are they numbered or coloured?

 

[pauldazzle]

Relay 109 I think, maybe someone can confirm?

 

[moggie93]

I always thought if relay 109 was busted the car would not start. My car will start and idles at approx. 12-1300 rpm.

 

[Broken Byzan]

It'll start but no throttle. And given you have no comms either, i'd guess that its not powering up

 

[moggie93]

Ok thanks, is there a way to bypass that relay to check if that's the problem?

 

[Broken Byzan]

er, not without wiring diargam handy. It should click on with ign and stay on for about 10mins after

 

[moggie93]

thanks. I'll get the ecu out tomorrow and see how the relay looks.

 

[moggie93]

Right guys a wee update.
Dismanteled the ecu cover and no sign of water ingress.
All relays were cleaned and put back in.
I took the panel off around the pedals and noticed that the 50 A fuse was very corroded so it was cleaned and replaced and seems ok.
I changed my throttle pedal for one of a mk4 golf, car now idles ok and revs but the EML,Glow plug light and the traction control are still on.
I'm going to get another throttle pedal and see how it goes.

 

[variosso]

Glow plug light and limp mode could have something to do with an EGR valve. Not sure on the traction control light though, they may be a complete coincidence.

 

[moggie93]

Glow plug light and limp mode could have something to do with an EGR valve. Not sure on the traction control light though, they may be a complete coincidence.

Egr valve has been deleted ,and removed from ecu over 2yrs ago.
New throttle pedal and a new 219 relay have been ordered. Fingers crossed this should sort it.

 

[moggie93]

Today I replaced relay No 219.Car started and all seems to be fine. I also plugged in a copy of vagcom. Still no communication with the engine ecu.

 

[Pork789]

New throttle pedal fix this on mine! Fingers crossed dude!

 

[moggie93]

New throttle peddle made no difference. New master relay and a lot of connector cleaning solved the problem on mine.