Have a 1996 XJR in for transmission service and the mechanic has run out of ideas and says no parts are available and is giving the car back unrepaired. Would appreciate any ideas, or recommendation for a shop in SF / Bay Area. I’m thoroughly disappointed in this “euro specialist” who claimed he knew what to do. He gave up… I’m thinking a non-Jaguar trans shop to work on the 4L80E. Any reason they couldn’t?

Currently the car won’t shift from 2nd gear (it will occasionally, but very rough and not consistently.) Codes were P0753 P0758 for the A and B solenoids and P1775. All solenoids, speed sensors, and internal wiring harness replaced. External harness checked for continuity and stretch / rubbing etc. and it seems fine. Trans TCM plug checked and it’s tight. Car has 70k miles and has been pretty well babied / garaged and is extra clean.

Any thoughts on repairing / replacing the trans? I’m resigned to a whole new unit if necessary… Are there any recommendations for sourcing a 4L80E? I have yet to call every local trans shop to see if they’d work on it, but a few calls ended with “we don’t service Jaguar.” Any recommendations in the Bay Area?

Thanks

 

I guess you already know but, the bellhousing Jaguar specific as is the electrical connector so normal GM 4l80 will not fit as direct replacement. Maintenance parts (fluid, filters, solenoids, bands, friction plates and such) should be bog standard gm stuff if I have understood from the interwebs.

Would it make sense to check other car forums also for transmission shop recommendations or just a useless trip down to rabbit hole? As I was bit bored and between things at work

https://www.hotrodders.com/threads/t...y-area.526615/
https://www.impalassforum.com/threads/tranny-qs.539673/



[edit]
I attached the error code list (originally uploaded by motorcarman) here also;
.

 

G’day Pete,

I recently had my XJ12 gearbox, a 4L80E same as in your XJR, completely rebuilt by a local transmission workshop, not Jag specific and it now performs perfectly.

Any shop familiar with the 4L80E transmission should be able to do the work you want done and there shouldn’t be any shortage of them where you are after all it is a GM Autobox.

Cheers,
Jeff.

P.S. Have a read of this, the problem with my Autobox was the AFL valve which leads to all sorts of strange behaviour.AFL Valve.

1993 to 2018 General Motors vehicles equipped with 4L60E, 4L65E, 4L70E, 4L75E and 4L80Eautomatic transmissions often wear out the actuator feed limit (AFL) valve bore. As a result, inadequate pressure rise and shift solenoid feed oil loss can occur. This can cause trouble codes, wrong gear starts, falls out of gear and clutch plate burn-up.

The purpose of the actuator feed limit valve is to limit the pressure going to the actuators (aka shift solenoids). The AFL valve spring is calibrated to prevent the pressure from ever exceeding a predetermined pressure, no matter what the main line pressure is. This is necessary to prevent more fluid from being fed to the solenoids than they can physically exhaust and to limit the maximum line pressure output.

On one hand, if the pressure feed to the ON/OFF shift solenoids is higher or lower than intended, the shift valves controlled by those solenoids may not do what they should. For example, too much pressure could flood the shift solenoids, making them act as mechanically stuck closed solenoids. Alternatively, not enough pressure could make them act as mechanically stuck open solenoids. As a result, the transmission can have wrong gear starts, or fall out of gear.

On the other hand, for pulse width modulated (PWM) solenoids like the line pressure control solenoid (PCS), if the feed pressure is too high or too low, the consequences can be detrimental. The PCS output controls the line pressure based on the calculated load from the computer. Consequently, if the AFL pressure feeding the PCS solenoid is too high or too low, the line pressure output will also be too high or too low. As a result, the transmission will either slip and burn frictions, or have hash shifts.



PWM/TCCValve

1991 to 2013 newer General Motors vehicles equipped with 4L80E and 4L85E automatic transmissions often wear out the torque converter clutch (TCC) regulator valve bore in the valve body.

The TCC regulator valve function is to regulate the torque converter clutch apply pressure. The computer varies the pulse width modulation of the TCC PWM solenoid, which regulates the apply pressure of the lock-up clutch. Because of the constant PWM solenoid induced oscillation, over time, excessive wear of the bore occurs. As a result, the computer loses the ability to control the lock-up clutch apply rate and slip rate properly due to the loss of TCC apply pressure.

 

You can try getting your parts here.

jaguarheaven.com

They are Jaguar Heaven Auto Dismantlers located in Stockton, CA

See if the mechanic can get parts from here.

Good luck!
-Jas

 

I would suggest giving Richard Critch a call at Precision Transmission in Amarillo Texas (806) 372-2210 He has an extensive reputation with transmissions and may be able to take care of your. Can't hurt to give him a call.

Darren M.

 

his youtube channel is very popular and the work he does is second to none. i bet he’s swamped.

 

Thanks for all the great suggestions everyone - much appreciated

 

The internal parts are all standard GM, with the exception of the wiring harness and plug, so any shop familiar with GM's should be able to rebuild it