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95 grand cherokee od light stuck in third

14K views 22 replies 6 participants last post by  patrick11981 
#1 ·
Ive had the governor switches replaced, but heres the problem. when its cold like 25 or below when you crank it in the mornings the od light stays on and the trans is stuck in third after you drive it about 10 miles and cut the vehicle of the light goes off. It wont come on every morning. Ive also noticed that if i leave the heat selecter switch on it does it all the time, but if the selector switch is in the off position it dont do it as much, sounds crazy i know but it semms to be involved. Its a 95 jeep grand cherokee with a 4.0 and 4 wheel drive. Im new here and i have searched the forums but havnt found anything, im running out of options so thanks for any help.
 
#2 ·
i doubt that the heater control has anything to do with the overdrive circuit. The od switch goes directly to the PCM. The switch is a momentary type, hit it once, it turns off the over drive seleniod & turns on the lamp. Hit it again tells PCM to re-energize the selenoid & turns off the lamp. I would suspect the switch. Pull the switch & check for continuity it should only read when pressed. I had a car that when it got extremely cold the horn would turn on. Steering wheel horn switch pad was bad.
 
#7 ·
Its in limp mode. You will not have any gear other than 3rd. Sounds like it needs to warm up before you can drive it.

Driving it while in limp mode will kill the transmission very quickly. Find the problem before you need a new tranny.
 
#9 ·
warming up the engine doesn't do anything for the transmission, which is what i was saying needed to warm up before functioning right. i think you have a bad gov pressure/temperature sensor(same unit).

try warming up the jeep while the tranny is in neutral and see if that does anything for you(the tranny won't circulate fluid unless it is in a drive gear or neutral).
 
#10 ·
the software that controls the transmission is programmed not to allow 4th gear if it thinks the trans is too cold

common complaint when I worked at the dealership with jeeps and dakotas

I'm sure there is a TSB explaining it , also chrysler offers a software update which will allow 4th when it is cold but it comes with a warning of possible trans damage
 
#14 ·
then you have a bigger problem.

check the relays in the power distribution center.

check the wiring to the main tranny plug for any worn through wires.

after that you can start digging into the transmission valve body.
 
#20 ·
Under discriptions and operations of governor pressure sensor/thermistor......the OD light will come on by itself if the thermistor senses the transmission is above 260 deg. and will not allow OD. Ratmonkey maybe correct in suspecting this part, it sounds as though Rat.. and Baxy have much knowledge with this stuff......

code 21...is set by the upstream os failing to reach operating temp in a set amount of time after a cold start
code 22...is set by Engine coolant temperature sensor voltages registering to high or to low.....
code 23...is set by Intake air temp sensor voltages too high or too low......

could you have an open thermostat? if running heater only makes you warm. Just a thought.
 
#22 ·
dont think i have a trans relay, tcm just has a fuse, i have a autoshutdown relay that i switch out and it didnt help. If i have a trans relay where would it be? Im thinking about replacing the tcm, do i have to take it out and get the numbers off it or can i run a vin to see which one i need?
 
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