Electrical gremlins - need help

[Ericboberic]

For several weeks i’ve been having random warning lights show up on my dash. The immobiliser light goes up too and if i stop the engine it won’t let it start unless i wait with the key in the ignition five to ten minutes.
Brought it to a mechanic who did something then it worked for a few weeks but started the same problems again.

i removed the ecu, cleaned the terminals, also sanded the battery terminals.
I ran a vcds that showed a bunch of errors. I cleared them all but the warning lights came back again.

also, the mileage just shows a bunch of lines.

any ideas? Is it the ecu?
Thanks!

 

[afarfalla]

module under the driver seat is wet

 

[Ericboberic]

Just checked it, it seems dry. Could there be a problem with the module itself?

 

[afarfalla]

bad ground check harness splices and the gnd under ecu on the firewall

 

[auntulna]

Yep. At first touch, it may feel dry, the carpet pad can soak up a lot of water. It's sometimes only when you open the module and follow the wires toward the front that you find corrosion. You should unwrap the tape and separate them, pull on them, then you'll know for sure.

 

[50harleyrider]

also if you have VCDS, do a scan and see if you have one wire or two wire error message for CAN. Also look closely at the CAN wiring near the convenience module where the wires converge, the connection will dissolve over time. could have been wet along its' life. The nature of CAN wiring itself being twisted causes stresses in the wires. All kinds of weird stuff happens when CAN wiring gets messed up. It is the information highway.

 

[Ericboberic]

Thank you everyone for the feedback. I pulled out the convenience module, removed the connectors, and opened it up. Everything seemed dry. When i put it all together, it continued to do the same thing. I looked at the wires leading to the module, they also seem fine. Here are some photos and a video of what is happening:

Eric Lenouvel

Explore Eric Lenouvel’s 11 photos on Flickr!

www.flickr.com

any other advice?

thanks!!!

 

[afarfalla]

key worn out, WD 40 into the key slot

 

[Tom in PT]

Rodents? Look for nests and droppings. They can get into the interior of the car, and the engine bay.

 

[zzdiesel]

Are the battery and alternator good? Check voltage.
It might be worthwhile to clean all the grounds. There was a thread in the distant past that listed the ground locations.
this is the kind of thing that can drive you nuts, good luck.