Next problem: I finished replacing the starter and installed a check valve in front of the filter. When I got it off the jack stands and went for a test drive the transmission wouldn't shift on it's own. I had the same problem on my 88 and did the diags on it but, I've forgotten the procedure. If someone would jog my old brain and lay out the procedure and solenoid parameters for me I would appreciate it. Thanks

 

I think in a 1990 you should have a fuse down by the TCU, image courtesy of Cruiser54, check that one out.


As for the solenoids, check for resistance on those 3 pins against a ground point, it should be 11-15 Ohms.

 

Thank you Boxburn! Haven't heard from you for a while, it's always a pleasure. Thanks to Cruiser for his foresight and insight. This should do the trick. If it's solenoid #2, I have one that I bought for my 88, but I hope it's the fuse. Thanks again.

 

No problem. I'm a lot less active on here than I used to be but pop back every now and again. Glad to be of assistance though.

 

Slacker!! We've missed you.

 

Boxburn, the tcu fuse is good. It's under the glove box on my 90. So I guess it's on to the solenoids. By the way, which color relates to which solenoid?

 

Yellow 1, green 2 & red 3.

Make sure the contacts in both side of that plug look good & if you get a bad ohm reading, while less likely, it could be a wiring fault so inspect the harness before jumping into the pan.

I joined this forum due to a problematic XJ, and solenoids was either my first or one of my very early issues this forum helped me with. The past 2 years have been for the most part smooth sailing so my head moved away from XJ problems ​​​​​​​

 

I checked solenoid resistance at the 7pin connector and all is good. I need to know what pin is the ground. I have a spare tcu if that becomes necessary and the tcu fuse is good. I really suspect a bad ground. Also, I can't read the numbering in this photo sent by Boxburn. When I blow it up it just gets fuzzy like my old eyes. If someone could enlighten me, it will be much appreciated. Thanks.

 

B is the ground. Looks like pin C5 on the TCU should also be ground.

 

I take the ground and solder a wire to it add a 2nd ground on it and then seal up the wire .

 

homestd, you are familiar with the engine dipstick grounds, right?

 

10-4 cleaned and sprayed quite a while back. I had replaced the starter and wiped oil off the oil pan and transmission. It was fine when I started and I don't think I hit anything with the rag. The starter install was nothing unusual but **** happens and now I have to find it. I want my overdrive back.

 

Darn those pesky users and their blurry pictures!

 

The solenoids themselves only have a single wire and ground through the transmission body.

 

Ok, I'm back. The "B" pin is grounded. Pegged the meter. Solenoids test good. What's next??