Had an issue with the 1996 XJS transmission…. The transmission light came on and I was stuck in 3rd gear. I pulled over, turned the car off/on and light with issue was gone. I was hoping it was just a weird random occurrence.

On my way home, it happened again. This time on the highway. No big deal, was able to get it home and pull the code.

P0758 - something about transmission shifter solenoid B

I went through my records, and although the fluid seemed red, it turns out the fluid is 7 years old and has over 60,000 miles on it. Yikes!

I sent it to the shop to get the fluid flushed. Hopefully that solves the problem. When I dropped it off, I got a check engine light, with the following code.

P1775 - No data exchange between ECM and TCM because of internal fault in the switch

or

Faulty Crank sensor

Im assuming it’s the first one.

Anyone have any experience with this. I went through the forums, but I didn’t find much. I found a few posts that replaced the solenoid, the TCM, neither resolving the problem. I also found someone replaced the transmission module harness, but no one ever came back to confirm success/defeat. I hate when that happens.

 

That fluid would be my 1st go to.

Both my X300 had filthy trans fluid, and it took a good number of drop and refill to get it clean gently, so as not to "shock" the internals.

The 3.2 responded quicker than the R, but both up to spec without lights etc after 8 or so drop and refills. Boring I know, but that has been my method of refreshing trans fluid since 1968, dont trust flush machines or the operators.

Both my S Types and the X Type, had trans fluid blacker than engine oil when 1st arrived. Same method, sweet as I like now.

Good luck

 

Vee
Your line "P1775 - No data exchange between ECM and TCM because of internal fault in the switch"

I have no direct knowledge; but dimly in my mind I have an idea that I read somewhere that there is some mode control switch (or some such) in the gearbox that goes home. PTJS1 will certainly know, if after the flush it continues to happen.

 

I was getting P1775 when my car was stalling - I think it was a symptom rather than a cause.

 

Agreed, especially since the engine never stalled.

The only codes this engine enjoys doling out are the ones that tell you what just happened, without indicating why.

 

Vee,

A couple of thoughts:

If your guys are not doing a full flush through of the fluid, but just doing a drain of the sump and refill, then you need to change the fluid a number of times to get it properly clean.
A simple sump drain will only pull about 2.45 litres of teh total of the stated 9 litre capacity in teh system. Therefore you'll still have 73% of the dirty fluid remaining after refill. As previously reported, I did 6 drain and refills on mine with 10 mile intervals on cycling the box, which gets you down the old fluid down to about 13%. Fluid is cheap, gearboxes aren't!

Obviously if they do a proper pumped flush of all the fluid through the system, that's a different matter. but most shops won't do that.

As regards the fault codes, the 0758 relates to a solenoid as you know, I've heard of how it can just be a dodgy connection causing that. And the 1775 is merely the TCM telling the ecu to throw the warning light to the driver. That's almost definitely just a result of the solenoid fault throwing.

I'd be minded to get the fluid sorted, reset the codes and see if the 0758 throws again. If it does, I'd then start looking at the wiring and the TCM connections.

Good luck getting it sorted.

Paul

 

ptjs1,

Yeah, that's about the conclusion I got to reading through the forums.

The only part I am surprised by, is the transmission fluid dump and refill. I did pay for a full fluid exchange, and that's what they did. However, if I was to dump the fluid myself, I would only be able to drain 2.45 liters of 9 liters? I am shocked at how little I would be able to dump myself. Are you basing that from sucking the fluid out from the dipstick hole, or by draining it at the pan?

Thanks.

 

Vee,

Jaguar quote the total fluid capacity of the 4 litre auto system at 9 litres. If I syphon via the dipstick until dry, and then also undo the sump plug, I only get about 2.45 litres. The most that I've got on any of the changes is 2.60 litres. If you drop the sump and change the filter, you naturally get a bit more, but not that much There is clearly a very large percentage of fluid retained within the transmission, the oil cooler pipes and the oil cooler itself.

That's why I'd always recommend a power flush if you can find someone to do it. The other way is to disconnect the return pipe from the cooler and direct it into a large receptacle, then run the engine and fill quickly through the dipstick whilst it is pumping out of the return from the cooler. It's a bit tricky as you have to try and balance the total fluid going in and out. I was going to do that, but the access to the connection of the return pipe is really difficult at the top of the box, and the insulation started to crumble away. So I gave up and did the multi-change route instead.

As you can imagine, most owners just ask the shop to do a fluid and filter change, which I think is quite dangerous, as most places won't do a proper flush and will just end up replacing less than 3 litres. And the owners won't be aware that they are running round with over 70% of the dirty fluid still in the system.

Once your filter and fluid has been changed, irrespective of how much fluid has been changed, I would then just drain the 2.45 litres of the sump and refill every year regardless. At least you'll have fairly clean fluid all the time.

Good luck with whatever you decide!

Cheers

Paul

 

I appreciate your response. My service manual indicates that I would expect 4 liters to drain out of the drain plug AND dipstick tube union.

Always great to hear real world results.

Im told by the shop that I ordered and got a full fluid exchange. Will keep you posted.

 

It's only been one drive, but the transmission fluid replacement seems to have done the trick. Will report back if anything changes, probably will not report back if the code does not return.

 

It's back. p0758 and p1775.

Seems I've got to find the ground point(s) for Solenoid B, to make sure they're clean.

I guess I also have to find the connection between the TCM and Solenoid B....

 

Car is back from transmission specialist. They didn’t charge me much because they didn’t find the problem. They tested solenoid b and it tested good. They recommended swapping out the transmission ECU.

I bought an ECU and same problem….so it’s gonna be a wiring/connection issue?

I trust the tranny shop. So the solenoid doesn’t need to be replaced.

I swapped out the ECU, so that gets crossed off the list.

Am I simply taking ohm readings from the connector at the transmission and the ECU?

Should I make plans to replace the plug at the transmission?

Is there anywhere else I should be looking at?

 

I noticed that the XJS used the same ZF 4HP24 transmission for MYs 1989-1996 for the non v12 engines.

Would anyone know if the harness changed for the different model years? I’m having trouble finding one.

 

Vee,.

The ZF 4HP24 only went into the XJS as from the intro of the 4 litre engine for the facelift model from 91.

Jaguar quote 13 different part numbers for the transmission harness depending on where it sits in the build sequences, and whether it's a Coupe or Convertible, or even if its a 2 seater or a 2+2. I don't know what any of the differences are. If you need a harness, maybe best to just source one for your late 2+2 Convertible which is the most numerous variant anyway.

Cheers

Paul

 

The zf 4hp24 has been used a long time and in a lot of cars. Is there any way to do some cross-reference with the codes and see what comes back? Or, are the codes and code numbers specific to jaguar. I have a zf 6hp26 in my XKR and due to the car having spent time in a lake I needed to go digging to get answers - in that BMW forums were very very helpful. As was the zf sight itself AND a guy named Klaus at The CTSC Transmission Company... He's hard to get a hold of but WILL reply to emails.

 

Looking up the wiring diagram, it does reveal that the connector is a 9-way Hellerman Deutsch connector….now to find which one.

 

Deleted

 

Pulled the connector at the transmission...its wet with transmission fluid. I flushed it with contact cleaner spray.

I also checked the continuity between Solenoid 2 pin K and the corresponding Pin 24 on the transmission ECU harness. I got an ohm reading of about 0.75. I stuck a common nail in both female harnesses and then connected them with alligator clips and 16 awg wire.

I'm gonna take continuity readings for the remaining pins at the tranny harness and rub in some Lubrimatic Electrical Contact Grease (not dielectric grease) and see what happens?

Any suggestions while I'm doing this?

 

So….I checked continuity on all pins. Everything checked out.

I cleaned the connector, and greased the pins.

Tightened up the somewhat loose male connector with a 30mm socket.

Reconnected it, and took a spin around the block….no change.

Not sure what I can check next.

 

When I checked the pins using the ohm setting on my multimeter, should I have checked all the other (relevant) pins while there?

For instance, when I had a probe tacked on to the solenoid 2 connector “K” at the transmission harness, once I confirmed continuity at the transmission ECU harness position “24”, I should have checked the other relevant positions? (38, 6, 46, 2, 5, 44, 42 and 19). Isn’t that the way to check for shorts?