1994 XJS 4.0 with 114k

While I was driving the car would not shift from 2nd to 3rd gear. I stepped on the gas and then a loud clunking happened and the car jerked into 3rd gear. Then the tranny light came on and the car started clunking/ jerking into all gears. Even when downshifting. I pulled into a gas station and checked the fluid, it seemed ok, if anything a tad above the full max mark. I then turned the car off and back on and then it started driving normally again. I got it home and now I am afraid to drive it.

I just ordered a filter for the tranny, even though the fluid looks good, I am not sure when the previous owner serviced it.

Also, I had the car in the N mode. I usually drive in the S mode. Not sure if that would cause it.

I read somewhere about a modulator possibly causing this. Dows anyone know if this is a possible culprit?

 

I'll start by saying you don't have a TH400 transmission. You have a "ZF" transmission.

I'll end by saying i can't help, because I have no experience with ZF transmissions.

Someone else will chime in

Cheers
DD

 

Thanks for the reply. For some reason I though it was the TH400. I will double check, though I think you are right.

It happened again tonight. I start the car and take off. The transmission light stays on and the gears abruptly clunk into place. It shifts when it si suppose to but it just clunks and the car jolts as its switching gears. I turned teh ignition off and back on again and the car drove fine. This is twice in two days now. Since turning the ignition on and off solves the problem Im guessing that is is an electronic issue? Could it be the TBS? Or possible the Transmission control module? Any one else have an idea?

The Jag mechanic said it would cost $140 to look at it... He also said they dont usually throw codes in this situation... Anyway I scheduled an appointment in a couple weeks, the soonest I could get. Hopefully I will figure it out before going to him.

 

sounds like your line pressure is sky high. if this was a 400 i would tell you to check your vacuum hoses running to the diaphragm on the side of the trans.

 

My was doing the same thing: '93 4.0 convertible. Turned out the TPS was failing. It finally gave up the ghost, was replaced and since, the tranny problems have not come back. The transmission module gets signal from the TPS, apparently, and the bad one was confusing the transmission chip. Seems feasible. I'm just glad the transmission faults have quit.

 

TPS will do it too. they generally tell the transmission when to shift, the RPM's necessary to achieve the desirable gear, etc.
this is probably the issue since you said it wouldnt shift into 4th.