I've searched the s type forum and can't find how to remove ECM. I have glovebox removed and see two bolts on either side of the module that need removal. I assume I need to remove windshield wiper cowl and pollen filter to get to firewall to remove another bolt holding ECM harness to the module? My engine starts intermittently and throw out different DTCs, also gearbox fault, restricted driving, all which usually start after snowstorm, rainstorm, or car wash... Water intrusion and corrosion in the ECM ? I see some water deposits in prime areas... Thanks for any help!

2003 jaguar s type 4.2L

 

I think you've got classic water in the trunk problems. Have a look around the spare tire well for high tide marks.

 

What is going underwater in the trunk?

 

The spare tire well fills with water and soaks the computers and wiring. All sorts of weird side effects

 

Known problem in the S-Type. The fix involves sealing at the cowl and has
been described before.

As for removing the ECM, maybe someone who owns an S-Type will come
along to advise further, or you can look at JTIS.

 

Tried to get the JTIS downloaded and getting error message. Just wondering if I need to remove cowl, pollen filter, etc in engine compartment.....to get to that one bolt on harness to ECM?...

 

You want to be 100% sure it's the PCM (ECM) that's a problem because it nearly always isn't. By then you've gone to lots of trouble for nothing.

Much more common is water/damp in the trunk. Even more common is a failing battery!

What makes you think it's the PCM?

 

Agreed on the battery. There usually isn't a correlation with that and intrusion of water though.

 

The battery checks out with 696 CCA out of a 900 CCA battery... I did find water in the battery area though so maybe it's getting into fuse box when I hit bumps... I'll try putting in a drain and checking the fuse box and wires for water and corrosion ... I don't think its the PCM, more likely ECM if it still throws out random codes after I install drain...it is a known problem with water intrusion into the ECM after rains, snows, and car washes... It follows the harness in the engine compartment into the ECM...

 

I'd fix the water problem first. Drilling a hole in the trunk will give you rust.

If it was me I'd pull the trim in the trunk and then vacuum the trunk clean and dry. Tape newspaper all around the inside. Close the trunk up and use a garden hose to find the leak. Fix the leak then while the trim is off check for corrosion. Sand any rust off and repaint n' clear coat the bottom of the trunk. Then see if your problems persist. Just my .02.

 

If water's got into the rear fuse box and/or any modules and/or harnesses you may end having to replace it/them.

 

The trunk should drain even if water gets in so I would take all the spare tire stuff out and give it all a good cleaning. Probably AFTER you find the leak. Try to not drill anymore holes.

Look at the tail lights and the trunk rubber seal. Both have been reported leak area's. I usually have to get locked in the trunk with a flashlight to find the leaks.

Let us know how the newspaper idea works. Might be a better way?
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There's a rubber plug on the floor of the trunk that can be removed to let the water drain.

 

Are there electrical tests for the different modules?

 

See JTIS for pinpoint and electrical guide.

 

I cleaned out the trunk and found the wiring harness to the rear parking aid module corroded and with high dried water marks...not sure that would cause the gearbox fault so I will continue checking fuses and relays as well as corroded grounds etc.. see attached picture of the rear parking aid module!

 

I'd suggest cleaning / drying the whole area properly, then, once completely dry a liberal sprinkling of talcum powder and plentiful use of a garden hose will clearly show leak points!

 

I cleaned up the trunk as well as the rear parking aid module...no wonder it wasn't working! I spread a little talcum powder around the perimeter of the trunk and hit it with hose ... Found a leak around the left tail light... I recall someone on the forums had the same problem so I'll look it up... Checked the fuses and found one missing as well as 15 others Mis-sized!

 

Yes, the taillights are a well known ingress point.

 

Looks like you found your problem!

I think the last guy did not know about the water problem and started removing/resizing the fuses.

Let us know if you get it fixed too!
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