Speedometer won't work after resetting check engine light

Carve

Carve

TJ Enthusiast
Joined
Apr 2, 2018
Messages
130
Location
Albuquerque, NM, USA
I was resetting a check engine light yesterday, but was in a hurry because my friends were about to leave. Instead of leaving the negative cable off the battery for a few minutes, I touched the cable to the positive side to discharge any residual voltage in the system. There was a tiny spark. Everything works fine except the speedometer. I can't find a fuse for it. Did I fry it? I pulled all the small fuses under the hood, and also the "instrument cluster" fuse behind the glove box. They look OK
 
What codes did you have? You probably didn't fry it. The VSS uses the same reference voltage as several other sensors on the Jeep, if that voltage is screwy the VSS wont work so codes might help find that issue. Also you might inspect the wires at the transfer case and the VSS itself.
 
Sounds like pulling the cluster and cleaning the terminals on the back might be a good idea, the cluster isn't sending the correct messages. I've heard that the wires can get corroded, hopefully the zap just pushed a poor connection over the edge.
 
You can test the speedo needle by doing a cluster test, I think you hold the odometer reset down and turn on the Jeep or something like that.
 
Thanks.
pagrey said:
You can test the speedo needle by doing a cluster test, I think you hold the odometer reset down and turn on the Jeep or something like that.
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I just tried it and the speedometer did move. So...it works mechanically, the electronic signal is being broadcast...they just aren't working together. The signal isn't getting to the speedo.
 
I think it's eleven screws total to pull the cluster, I just cleaned mine out. It helps if you have a short Philips for the top three that hold the bezel. That's the next thing I might do and if that doesn't help I'd also clean the PCM connectors. A spray electrical contact cleaner will really help. i think the cluster and PCM only communicate with a single violet wire, maybe with a yellow stripe so that's the important one. You could check grounds but that's kinda grasping at straws.
 
The DRB thing sucks, I've got one if you want to drive to California. Battery disconnect is there although I've never used that function. I've shorted mine together without a problem, I don't think it's normal but it looks like the scan tool fixes it.
 
Thanks. Guess I'm off to the dealer. What should this cost? I think it might be because the prior owner had a superchips flash on it. He actually works at the dealer, so maybe he can hook me up...but his dealer is 45 minutes away and I have another 5 minutes away
 
Might be helpful for the guy that did the flash to call your local dealership to help them get it done. Most techs are using the DRB emulator on the Chrysler computer system now and not the real thing. I have no idea how well most guys know the system or what the limitations really are. It all depends on the dealership and service manager, it's a crap-shoot in my experience.
 
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