BEW Temp sensor

[smokinVE]

2004 BEW Jetta. I'm having an issue when the engine is cold the car says it's at 260+ and the idiot light comes on fans go high and AC doesn't work. I drive it a few minutes and it drops down to 120 and all operates as it should. Replaced the temp sensor with no change. Looked at scan tool data and the ECM is seeing the correct info. I cannot access the Cluster info with the scanner I have access to so I started to test wires to cluster they pass. OHM readings with the sensor and the wire at the cluster all good. I can un plug the coolant temp sensor and the gauge goes cold. Does anyone know how the logic works for the cluster? I'd hate to throw a XXX$ cluster at it without knowing its bad. Also I've both shorted and unplugged the coolant level sensor with no change. I did find really high resistance on the ground side of the temp sensor for the cluster, got that fixed but didn't help. That could have been the route failure and took out the cluster? BUT most of the gauges ground off of the problem I found and I have no other problems with the car.


AND I'd love to dig up Adolph and kick him square in the sack for the VW schematics!!!! I'm working off allData, so hopefully the real VW ones are better than what I'm working with...

[smokinVE]

I forgot to mention, I've had some earlier issues with the car. It would wig out after a heat soak, clock would go crazy (in the cluster). One time it went into theft protection, all I had to do to get it to start was unhook the battery for a few and it fired up. My sunroof drain was plugged up and my driver floor would get soaked after a good rain. I got that fixed and I haven't had any weird cluster/theft issues for a good 4-6 months but this temp gauge thing started up 3-4 weeks ago. Everything points to a internal cluster fault but I like to prove something before I chuck parts at it.

[smokinVE]

Educated guesses?

No WV techs on here?

[RDPsmoker]

Can you pin test at the cluster and verify the ohms is the same as the sensor. If it's ruffly the same at the sensor and going into the cluster that would point me to a new cluster.

[smokinVE]

I can probably do that, I can lean the cluster out a decent amount and try to back probe it while still hooked to the sensor. The wiring is good up to the cluster. I just don't understand the logic? Does vw read that sensor for a bit and then switch over to the ECM for readings after it decides that input it invalid?

My next hillbilly fix is going to be to put the cluster side of the sensor on a toggle switch "disconnect" the sensor for start up and the first few miles of driving then flip the sensor back on. I'll see if that reads right and operates okay.

The schematic has a ground buss for the cluster that tests good even loaded to 5A. I loaded the signal side of the wiring also and it tested good. I'm lost, maybe I'll just install remote start and fire it up 5 minutes before I hop in..