XJ XJ6 / XJ8 / XJR ( X350 & X358 ) 2003 - 2009

X350 Gearbox Fault

Old 08-30-2017, 05:36 PM
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Originally Posted by Ed davies View Post
I know this is an old post but in case anyone has the same issue. The problem on my 2003 xj was the rear passenger side ABS/wheel speed sensor, It was sending the wrong signal to the gearbox ECU this was throwing up a gearbox failure warning, replaced the said sensor and all sorted.
Ed, how did you determine it was the ABS/wheel speed sensor? Did it throw another code? I'm only getting P0735.

Also, can someone explain what the e-clutch is? Is that a torque converter lock up?

Old 05-15-2019, 01:19 PM
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I was with a X350 4.2L with transmission fault, Restricted performances BUT no DTC on the transmission!! The only DTC was if I remember well P1643 no communication between TCM and ECM. (some time with this Can bus error too with ABS or Instrument cluster.
When I was starting, if I was needing to pull the accelerator the car was going in limp mode and was fixed in gear 3. If this was happening after few meters, the transmission was going in gear 5 (no light on the J gate etc.) So, I drove one year in gear 3 in city, gear 5 on speedway!!
I tried the ABS connector, Instrument cluster connectors, then controlled the can bus, I also connected the TCM can bus directly to the ECM bypassing the connector, changed TCM oil, verified level few times, reseted the TCM adaptation, etc... always the same! I tried to change the Valve body for another rebuilded, still the same problem! As the problem was CAN bus communication, between TCM and ECM I changed the valve body + TCM coming from another car and installed them in my car! Same problem again!!
Finally, I found why the transmission was jerky and limp mode and no CAN bus communication. It was exactly what I was meaning since few times.... ECM Torque signal fault. It was the ignition coils!! I changed all my coil, and my car worked normally!!! Big power, no can bus fault, no misfires etc. A new car!! Reason I was meaning, was when exiting from my underground box I was needing more power, so pedal going down and ... voila! communication fault, gear 3 or 5 blocked, no lights on the J Gate!
So, I was thinking the ECM is sending a Throttle position sensor which is like big acceleration, because as he coils was not firing correctly, the Transmission was thinking I needed big power!!
So, in conclusion, if the J-gate (sport button flash or stay fixed when you turn the key) or you have the Can bus error between the ECM and TCM then Limp mode etc. look at your coils, candles etc... principaly if you have DTC with misfires. Hope this could save money and time to many peoples with transmission problems!

Last edited by restorsc; 05-15-2019 at 09:48 PM.
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slmskrs (05-16-2019)
Old 05-15-2019, 01:29 PM
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I must say, that in the past I changed my ignitions coils few times, but no original coils, some aftermarket. Transmission worked one week / 2000 kms, then failed!
Now I bought more expansives coils from LUCAS (www.rld-autos.com) 57,48 €
and I have my 300 HP and transmission very smooth!
So, be carrefull of ship Ignitions coils....
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