Trans overtemp

Tiny
EVAN.P.MORRIS
  • MEMBER
  • 2005 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 96 MILES
2005 jeep grand cherokee laredo 4x4 3.7L a/t transmission, not sure what model. Was running very bad, several missfire and 02 codes. Replaced all plugs, bad coil, catalytic converters and both 02's on pass. Side bank. Now vehicle runs and drives great but after about 2 - 3 mile of normal driving trans temp gauge pegs, fans ramp up and trans overtemp warning on dash displays. After driving and temp gauge pegs, I pull the dipstick, fluid and dipstick is only moderately warm. Fluid condition fair at best, does not smell burnt and level ok. Checked wiring for disruption during repairs and found nothing. No blockages around oil coolers. All lines look ok. Used cheep hand scanner found no codes. Tried disconnecting battery, no change. I have a hard time believing this trans concern is coenceidental but I am finding nothing in lue of the repairs I made. Any ideas or known concerns like this? -Thank you for your time.
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Monday, January 3rd, 2011 AT 5:04 AM

3 Replies

Tiny
KHLOW2008
  • EXPERT
Symptoms indicates a false temperature reading rather than a fault in fluid cooling. It could be due to a faulty temperature sensoe or its wiring circuit.

Unplug the connectors at transmission and test the Dark Green/White wire for shorting to ground.
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Monday, January 3rd, 2011 AT 4:49 PM
Tiny
EVAN.P.MORRIS
  • MEMBER
My appologies! The temp gauge that was peging out was the engine temp not trans. The trans overtemp message did however come on. I suppose that is just related to some type of overheat stratigy though. Anyway I monitered coolent temp and let the vehicle idle for approx. 20 min. Pressure built and temp increased to about 115 before the fan came on. About 125 the fan ramped up speeds but the vehicle did not seem to be cooling down. I shut it down at about 135. I could unplug the temp sensor and watch it default to -40 then go back to normal when pluged in. The t-stat is attached to the lower hose on this vehicle. When I felt the upper hose it was hot. The lower hose was cold closest to the radiator but as I felt it from the radiator to the engine it got progressively hotter. The coolent looked ok, wires and connectors looked to be ok, there didn't appear to be any exhaust/compression bubbling in the coolent when I was running it. All fluids look ok. Seems to me like it would either be a faulty t-stat or sensor. Again though, i'm a little suspect after all the work that was just done. Any suggestions before I start shotgunnin parts? Thanks again for your time and sorry for the mix up before.
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Tuesday, January 4th, 2011 AT 6:38 AM
Tiny
KHLOW2008
  • EXPERT
From what you desscribed, I would suggest checking the thermostat. Seems it is no opening.

By the way is coolant level correct?
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Tuesday, January 4th, 2011 AT 2:42 PM

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