Mechanics

WITH FINICKY OVERDRIVE

1995 Jeep Grand Cherokee • 220,000 miles

I have a 1995 jeep grand cherokee 8 cylinder that intermittently won't shift into overdrive. When this symptom occurs it will continue to "not shift into overdrive" until the jeep is shut down and restarted. It will "never" correct itself if the ignition key is not cycled off and then back on. The transmission has recently been overhauled by an aftermarket transmission specialist and the PCM has recently been replaced by a Jeep dealership. Both the dealership and the transmission shop believe that it is not the transmission. It does not have a TCM (it is a 46RH transmission) and there are no codes stored in the PCM. It does seem to be temperature related, as there is no consistency and the frequency is unpredictable; each time you start the car it will either decide to work or not, approximately 50% of the time. Also the O.D. Light/switch in the dashboard appears to be working correctly. The jeep has been at the shop more times than I can count over the past 6 months and am no closer to an answer. Since I don't believe in coincidences, there are two more symptoms that the jeep has that may be relevant to mention;

1. If I lock the electric doors (which automatically sets the factory alarm) the alarm may randomly go off hours later, unprovoked by anyone.

2. Intermittently I will comeback to my truck hours after leaving it and will find the brake lights on. If I pull up on the brake pedal gently the brake lights will go out.

Is it possible that the brake switch could cause all three symptoms? I have tried to pull up on the brake pedal when it won't shift into overdrive, but it does not alter the behavior. Can anyone help me to remedy this problem, I am out of patience with this problem?
Avatar
BillNagel
May 28, 2012.



I misquoted above, I meant to say, "It does NOT seem to be temperature related".

Tiny
BillNagel
May 28, 2012.
Was the converter replaced at the overhaul?

This system works with pressure in the valve body, engine speed and yes, temperature is a factor.

If you have a thermostat in the cooling system that is not allowing the engine to reach normal operating temp, the overdrive will not work correctly.

Speed is also critical as the speed sensor will have to be confirmed with a scan tool to see what info is gathered.

Roy

ASEMaster6371
May 28, 2012.