Bustedback

My trusty 95ZJ 4.0 42RE has started acting weird just the other day. It shifts fine all through the gears, no slipping, fluid level is perfect and smells ok. When in overdrive if I hit a sharp bump or rough patch of road the transmission will downshift into third for a few seconds and then go back into overdrive. Sometimes it will do it when making a right sweeping turn at freeway speeds. Anybody ever encounter this problem?

dave1123

No, but it points to a loose connection in the overdrive solenoid circuit or a faulty temp sensor. Does the overdrive button still cause a downshift? My book says a loose or shorted button switch can cause that. The sweeping turn makes me think the temp sensor is not submerged at that time. This is just a guessing game. Hope it helps.

It's quite unusual for you to be asking for help!

Bustedback

I have an extra button, maybe I will swap it and see what happens. I was thinking it could be the governor pressure solenoid too.


I'm good at offering diagnostic advice for other people's rigs, but second guess my own rig. I need therapy.

dave1123

Sometimes we just need a sounding board. This forum is good for that!

My manual doesn't have your summa-time O/D symptom, but it does have a "no 3-4 upshift" section. They do also mention a overdrive piston seal failure, a blocked solenoid feed port in the valve body, or low hydraulic pressure, as well as the loose wire to the O/D solenoid or shorted O/D button switch or temperature thermistor failure. I'd say these are just places to look, because the O/D functions, just not all the time.

One of my Dad's sayings "That intermittent problem will NEVER show up in the presence of a mechanic!"