Limp home mode & transmission failure light
 

1994 xjs 4.0 , convertibleI have intermittent problems that seem to be tied to when the car gets hot. Transmission failure light comes on and car goes into limp home mode. I have changed the transmission fliter and fluid, cleaned wiring harness at transmission and transmission ECM, cleaned TPS connections and cleaned mass Air Flow - no sucess. may run for weeks at a time before it acts up. Does not give a code and can usually be reset by disconnecting battery - lately it has repeatedly failed imediately upon trying to move. Any help or suggestions appreciated. Have now replaced tranmission warning light relay. Thinking about transmission output speed sensor and possibly SV3 lock-torque converter lock-up switch. - any help or guidance appreciated!!!
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My first thought is the Transmission Power Relay. Should be in a blue base, above the right rear wheelarch.

Cheers,

I agree about the Blue Hella relay being the first thing to suspect. I usually suggest replacing all the blue relays that power important circuits.

Here is the TSB for diagnostics and replacement guidelines

bob gauff

Thanks I have swapped the trasmission power relay and t he transmission warning relay so I will need to drive it again when it is hot., Many times it runs fine for weeks at a time. This morning I pulled out of garage and the car sputtered and stopped - cheked gas and found fuel pump not working - did diagnostics and sure enough bad fuel pump relay, fortunately I bought an extra when I replaced the fuel pump.
I am trying something by removing all of the relays, claning them with contact cleaner and then putting corrosion inhibitor grease on the connections- I will see how that helps -Thanks for the reply!

tranny light.
 

after rebuilding tranny,replacing computer and many hours of contemplating what to do next,I READ ABOUT CHECKING THE RELAYS AND LIKE MAGIC PROBLEM SLOVED. Thanks jAGUAR FORUMS.COM....LIGHT IS OUT AND SHIFTING LIKE NEW TRANNY.

Hi,

I think I have may have the same transmission power relay issue and would like to change the relay. Can someone tell me where this relay is located on a 94 xjs v12 convertible?
Thanks for you help.

Just found the answer in previous post. sorry.