About once a month I get a Trans light come on and it starts to clunk into gear. it is only when I first start the car. If I pull over, turn the car off and back on the issue goes away and the Trans shifts smooth.
Any idea what this could be? It happened a month ago a.d I changed the fluid and filter. It just happened again.

 

ok, how bout some info? car, engine, trans, etc?

 

1994 XJS 4.0, 117k, fresh transmission fluid every 20-30k.

I noticed today that the light came on again while I started it. I tunred the car off and on again and the light went away. If I start to drive it with the transmisison light on the transmission will shift very rough and clunk into gear as stated. It always goes off when I turn the engine off and on again. Im at a loss.

 

I would start by checking the rotary switch on the side of the trans. It may need cleaning ,or adjusting; when you stop and re-start, you move the selector into park and back into drive, might be enough to improve contact. Is there a large, round electrical plug on your trans which is prone to leak oil?

good luck
Pete

 

There is a large round electrical connector. I did not notice any oil on it when I checked. I will take a closer look this time.

I think it does have something to do with me shifting it. I was start to think that it is happening because I start it and shift it into gear too quick, before the lights go off on the dash (check engine light, etc.). If I wait a moment it doesnt seem to ever do it. Im going to py closer attention to when it happens to see if it is in fact because I am not waiting for the ECU to process...

Maybe the processor on the ECU is getting slow with age? Just throwing possibilities out there. I cant see how this could be mechanical, unless it is as you say, in the switch. I am going to give it a good cleaning. Also, I noticed the TPS is beat up pretty bad and is missing the bottom. Im also thinking that this may be a possible issue? Seems odd though that it would only do it on initial start up if this is the case.

 

First thing to check/replace is the 'crappy blue Hella relays'.

I recommend replacing all the blue relays that power control modules.

bob gauff

 

good advice. i had to replace all the convertible top relays (purple), and the blue side light relay. Just discovered that there are more blue relays behind the instrument cluster. I would not be surprised at all if my problem lies with one of these relays.

the blue relays are actually made to high standards but they have an opening in the bottom that allows dirt to get in and render them useless. cleaning them is temporary because the coating gets destroyed. One is better off with crappy relays that are sealed imo.