I have a 2003 Jaguar S Type V8 Vin # SAJEA01UX3HM84660 . The car was driving in the rain in went into gearbox Fault and restricted performance, blowing the F33 TCM/ECM Control module 15amp fuse. I took the valance off and got to ECM behind the cabin filter and it was completely dry, I cleaned the drain to the left of it and used di-electric grease in the plug and around the seal of the cabin filter box. I put a new 15 amp fuse in and it started right up and was fine. I drove the car for 3 days locally and also kept it in the garage with hood open fan on and also running the dehumidifier. On the third day I drove about 8 miles and the car sat for 5 hrs I started the car to leave and again the F33 15amp fuse snapped (It was warm and sunny all week ). I put a new one in to get me home, for when this fuse snaps the car will not start. I then pretty much took all my kick panels out and seats went thru all my connections on the fuse boxes and modules and found no signs of dampness anywhere. I tested my battery and found it to be 2 things one it was about 50% and also the battery in the car was for a V6 not a V8. I put the car back together and bought a brand new correct original equipment battery and put a new fuse in and again as soon as it started the fuse snapped. I have come to find out the TCM is inside the Transmission and sometimes the boot for the plugs gets old and oil can leak in. But nothing I have read says this causes the fuse to fail with this condition. I don't want to take my transmission apart if there is a much simper solution. My technician is pushing me to have the TCM sent out and tested. Any advice would be greatly appreciated.




In this video it shows the procedure to replace the seal sleeve for the TCM






My gut is telling me I have a ground issue, I have attached a couple photo's as well.

 

Joshua, Joshua, Joshua... Sigh, there's no way we can help you will all of these precise details you have provided. We are much more accustomed to short posts hurriedly written in textese without punctuation, with scant technical details. I don't see how you can expect anybody to help with a post like that.

Wiring diagrams here:

http://www.jagrepair.com/images/Elec...al%20Guide.pdf


Your wayward fuse in shown in figure 01.2. Note how the circuit branches off to three other figures. Follow the bottom one (#75 in a square box) to figure 04.1 for the transmission.

Figure 04.1 is a bit confusing as it shows inputs for both the V6 and V8 versions. You obviously want the V8 version, with the corresponding #75. Note the capacitor on the harness feeding the transmission control module. If the capacitor was shorted across, that would definitely blow the fuse. Before doing anything too expensive, I'd suggest finding that capacitor and disconnecting it for testing. No idea of the exact location, but it may be wrapped inside the harness. Run your hand along the harness and you may find a lump.

 

I'm not seeing any reason to blame the TCM. Especially as the TCM never seems to cause such a fuse to blow.

More likely is something ordinary like a chafed harness.

You may have a power drain and I'd be sure to check very carefully as if any circuit is dubious it may also be the one that blows the fuse. (E.g. look for a tiny voltage drop across any fuse).

BTW my vote would be: this should not be a poll and anyway it's not common but instead appears the only one ever.

 

Found a mouse nest under the engine cover on passengers side of the fuel rail. I haven't found a wire damage there yet. I pulled the fuse box to see if maybe they got inside of that but no evidence of bad wires or creatures in there.

 

Small update- I found a mouse nest under the passenger side fuel rail, but found no damage to the wires there or inside the fuse panel under the hood. I then put a fuse in the car and it does not snap when you start the car or when you apply the brake or put it in gear. Once the car rolls that is when the fuse snaps. Engine light on, restricted performance and gearbox fault as well as apply the brake light came on this time.

 

Mouse may have chewed a wire...

 

You are making GREAT progress if you can reliably replicate when the fault occurs.

I'd suggest a special fuse panel ammeter for further troubleshooting:

Electronic Specialties Inc. Professional hand held automotive test equipment. #309 Fuse Buddy Mini Kit

This type plugs into the fuse panel socket. You could theoretically make the same amperage measurement with an ordinary multimeter, but most are limited to 10 amps. You're measuring 15+ amps. I have the Harbor Freight version of that fuse panel meter and it works great, but I had to rig up a special adapter for the physically smaller fuses on a Jaguar.

I wonder why the amperage increases as the car starts to move. Perhaps the overload happens as you shift into gear, but it's barely over the fuse rating. If so, maybe it takes a few seconds for the fuse to blow, which coincidentally is when you started to drive off. Hook up an ammeter and then you can know for sure.

 

Thank you, I can place the car in gear and out of gear switch gears and shut the car on and off, it isn't until the car moves under power that it generates the fuse to short.

 

Could be as simple as something flexing and makes the short circuit.

 

A few more variables you can introduce for troubleshooting.

Try starting out in a lower gear or reverse. Basically, anything but drive. See if that makes any difference.

Try changing how much throttle you give the engine as you try to drive off. If you normally give the engine a lot of gas to get moving, try creeping away at idle, or visa versa.

I've no idea how to interpret these variables if the fuse doesn't blow, but maybe somebody else will.

 

REPAIRED !!!!! SO Apparently the V6 wiring is in place for the transmission even though my car is a V8. I found 2 wires split between the transmission and the body, when the car torqued while moving it put enough pressure on the wires to short them out. Re positioned and repaired wires. Car is running A - OK>.


Thank you for all your help everyone !!!!

 

Excellent find, just as JagV8 suggested. Sure beats replacing the TCM as your mechanic was thinking.

One little detail has me scratching my head, though. Re: The unused V6 connector on a V8 car. It's very common for a manufacturer to include extra provisions in a wiring harness. It's much easier to make one common harness versus multiple option-specific variants. For example, my pickup has all the factory wiring provisions for some optional equipment that was not installed.

But on our cars, why is there an external difference between the V6 and V8 transmissions, requiring different connectors? It's the same basic transmission located in the same spot, isn't it? I'm certain there are internal differences, maybe software related, such as shift points, etc. But I'd think the basic externals would be the same, but obviously not if the harness includes engine-specific connectors.

Call me confused.