trans problem

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  #1  
Old 10-21-04, 02:42 PM
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Join Date: Feb 2004
Posts: 64
trans problem

this is one for transman
hi everybody, vehicle is a 93 grand cherokee, V8, 4speed+overdrive automatic, it wont shift into overdrive, also the shifting from 3rd to 4th is very
soft, one can barely tell when it does shift into 4th, almost not noticeable, i can only tell by the tach. fluid is clean and very normal looking,(i change it once a year) no burnt smell or particles in it. the same day it malfunctioned the speedometer also stopped working. dont know enough to know if those 2 are related. what do the smart guys think about this one ? Thanks,
mark
 
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  #2  
Old 10-21-04, 02:48 PM
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Join Date: Jan 2002
Location: Chicago
Posts: 1,915
This is probably due to a bad VSS (vehicle speed sensor). The trans uses it to determine shift points, and of course the speedometer uses it also. Does your odometer work?

Unfortunately I don't know much about Jeeps to tell you any more...
 
  #3  
Old 10-22-04, 05:04 AM
transman618
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No overdrive

Mark,

I agree on the VSS issue. The 3-4 shift on this trans is electronic. The 1-2 and 2-3 shifts are dependant on a governor. The 3-4 shift and TCC lockup are controlled by computer. Check the drivers side of the tailshaft on the transmission for the VSS. Check the wiring and plug first. If this sensor is bad, or the wiring is not connected, the trans will not shift into OD, the TCC will not lock up and the speedo will not work.


transman
 
  #4  
Old 10-25-04, 07:23 AM
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to answer trinitro, no the odometer also does not work.
thanks for the excellent advice transman, unfortunately, no luck yet.
I had the speed sensor tested (twice, 2 diff places) , tests as good.
It is a 3 prong plug. Wit engine on, prong 1 reads 5 volts, prong 2 reads nothing, prong 3 reads 1.6 volts. All the fuses in the vehicle are good.
The mechanism that turns the shaft of the speed sensor is also good , I was able to get a mini screwdriver in it, and it does turn it when the driveshaft moves. The problem does point at the VSS but everything in that area seems to be working, currently stumped. Any hints anyone ? Thanks
mark
 
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