mrc

Sometimes my 87 xj won't go into overdrive. First second and third all work normally all the time however on occasion it won't go into od when it shifts into od it just slips however if i stop shut it off and start it back up then od works like normal again. I have tried the trans switch in both comfort and power this makes no difference. I have spent the last week searching and reading about every thread to do with transmissions on here and tried the things suggested I have thought the problem was resolved several times only to have it show back up later. So far i have adjusted the tv cable, replaced and properly adjusted the tps from trans plug, refreshed all of the grounds and checked them for continuity, refreshed the c101, checked the solenoids with ohms meter all tested at 13-14 ohms, I have even tried switching the tcu to the one from my parts jeep also an 87 xj still no change sometimes it will just slip when trying to engage od but if shut off and restarted it works fine. What else should i check?
Thanks ahead for any help!

Turbo X_J

Internal pressure issue maybe, is the fluid (dex III/merc) clean?

mrc

It is dexIII/merc and its clean I changed the fluid and filter a year ago then had to do it again two months ago when the pan gasket started leaking. I was thinking it is probably electrical where it works just fine if i shut the jeep off and start it back up.

kjc

I'm not sure this is applicable to your vehicle, but on my '93 Laredo, the brake light switch affects OD and TC lockup. Just a shot in the dark, since you seem to have checked everything else.

cruiser54

Yep. How's your switch look?

mrc

I looked at the switch and cleaned it with electrical parts cleaner it seams fine to me is there a way to test it? I also noticed that mine only has one plug on it unlike the one in your pic but I should have the brake lights at least flash on if it's the switch making contact when it shouldn't. I hate intermittent problems like this because I never know when it will do it or if it is really fixed. I drove it around all day sunday with no problems only to have it do it again monday.

cruiser54

2 switches there. White one for TCC and cruise.

When switch is depressed, look for no continuity between terminals. When depressed, continuity.

1 up at the pivot is for brake lights.