erratic speedometer/trans

JSEsterly

JSEsterly

New Member
Joined
Jun 30, 2005
Location
Jacksonville
Ive got a 97 Grand Chero with a 4.0, 4x4.. Runs great until the a/c or heat is turned on then the speedometer jumps from 0 to 120 and anywhere in between.. the trans also starts acting up.. I have to pull over, turn off the jeep and restart it with e a/c and all that off... I replaced both speed/trans sensors.. cant think of anything else.. anyone ever have this problem?:confused:
 
I think I've seen on here where the speedo wire has a loose connection at the cluster. This might also be an input for the tranny controller so it freaks out. Try a search. Hope this helps.
 
Some cars use the speedo output as an input into the transmission controller to determine shifting. I suspect the cluster connector is intermittent. I would pull the cluster, put some vasoline on all the connectors and then plug them in several times to remove any oxidation. Jeeps have a bad reputation for crappy electrical connections.

I'm thursty.....:beer: :beer: :huggy:
 
I've had some Jeeps that came in the shop with all kinds of electrical problems and most of them came down to the alternator not charging enough. The BCM needs over 13 volts to work properly. I would check the alternator output with a DVOM with the A/C on blower on high and watch the voltage. Also if the battery is a little weak it can kill the alternator output voltage. Just a thought :)
 
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