Those codes suggest a CAN problem - such as a chafed cable causing a short.

That they're occasional means it may be hard to find, such as it needing to flex.

 

I pulled apart the ECM and took another look. I found a few traces around some capacitors that seem to be exposed completely.

Anyone think that this ECM is likely caput?

 

It is probably OK.
Someone has been in there previously (C423 has been replaced), and the exposed tracks are likely the result of a previous clean up of leaked electrolyte.

Since you already have it apart, I'd recommend changing all seven of the electrolytics. Even if they haven't leaked, they have deteriorated after 23 years. Give the affected areas on the PCB some TLC to remove any remaining crud and confirm all the tracks are intact.

I posted the Nichicon part #s and sources here:
https://www.jaguarforums.com/forum/x...6/#post1806456

May not help with the P1637, but it's worth doing and the parts are only around $5-6

 

Alright, game on car.

I managed to get my can bus analyzer back from a friend who was borrowing it, charged the battery up to 12.8v, plugged the logger in and drove the car around the block.


I have found that sometimes during logging the heartbeat messages are changing away to something other than 14.

I have confirmed over multiple different logs, because not each module exhibited the behavior in each log, that each module corresponding to 7d0, 7d1, 7d2, 7d3 respectively have reported their heartbeat message as f4 instead of 14.

This will happen for approximately 0.75 seconds or around 4-8 cycles depending on the module.

The rest of the time that these modules are reporting their heartbeat messages, they are all reporting 14 consistently.


It seems as though these might have a weak correlation with the time that the car is cranking to turn the engine on.
Do I just have a shitty battery and it isn't able to start the engine and power all of the modules at the same time? The battery is relatively new, but it did sit for 6 months straight without use or care.

 

I took the battery in and had it tested and it failed testing.

It only lasted a few months, or possibly was always bad.

New battery installed, small changes to car behavior, none that seem promising.

Check engine light went out for the first time in a long time, but then the abs module disconnected from the network, and the engine went into failsafe mode, check engine light came back on

 

Resolved!

It was ANOTHER bad ABS module.

Car is now smogged and titled and i have been flogging it, i think this is the slowest running car that I have ever owned.

 

Good to see you are making progress.

About the slowness, have you adjusted the throttle cable yet? That made a world of difference on mine.

 

I haven't tried to adjust the throttle cable yet, but i do need to adjust it. It is a touch too tight, the throttle pedal is super twitchy and i can feel tons of vibrations in the cable through to the foot pedal.

 

Congrats on smog.

Not sure if congratulations are in order for the record number of bad ABS modules installed.

 

Well, **** me, it broke again.


The car worked all yesterday. I drove it all over San Diego for about 10 hours and several hundred miles of different long and small trips.
I also smogged the vehicle on the dyno and it worked perfectly and passed smog with almost perfect numbers.

I just went to go drive right now and within 3 minutes of turning it on it popped up ABS/TRAC warnings and then within 10 seconds it put the engine into limp home mode and the transmission went into 4th.

For the love of god, someone help me lol

 

MH,

You’re cursed! WTF! After a successful few days enjoying the car.... then you find this.

Have you checked battery voltage and whether the alternator/generator is good? Is there a problem with the suppression smoothing the voltage?

Hard to believe your “umpteenth” ABS module has gone bad again.

 

After a full day of driving, and a night of sitting, the battery was still at 12.6V. The alternator is new and putting out 14.3v at the battery posts with the car running.

It has to be a loose connection somewhere in the car that is causing this now.

I think we have resolved all hardware / software non comformities.

Now we are dealing with a loose ground, or a plug that isn't making good contact, or a trace on a motherboard that is shorting against another one. Something of this sort.

 

+1 to JagV8 post 81 - probably a chaffed wire somewhere giving you an intermittent problem.

Worth starting at the big ABS connector pins, as you must have had it on/off a lot during your woes. Then chase them back, checking continuity PIN by PIN. Bugger of a job though! Don’t envy you.

If I had your problem I would rip the wiring loom from my scrap donor car and try putting in that first.

 

I tend to agree, but that was the first thing that I tried. I continuity checked, and checked voltages, for the can bus at every single plug that it is possible to do so at.
Everything appeared perfect.

Short of digging every wiring harness in the engine bay out of the car and cutting the looming to inspect, i don't have a reasonable way to trace down an intermittent chafing issue.
It never seems to do the same thing twice unfortunately.

 

Four days in a row now the car gives me troubles and throws abs errors and puts the engine and gearbox into failsafe mode until the car gets heat in the engine bay, then it will drive all day with no problems. Can throw the car backwards into a turn and hit the biggest potholes and never have a problem.

Still trying to locate and find any possible damaged wires or corrosion or something of the sort.

 

Gets better when it heats up? Sounds like a wonky connector expanding into the connection.

Does it happen immediately when cold, or during the pretty rapid warm up to nominal temperature?

 

I don't let it get warm before I drive it.

I turn it on and go almost immediately, the abs issues happen within 1-5 minutes of the car turning on.

It seems to happen by about the time i can get to 40 miles an hour on a residential street.


Then i shut the car off and let it heat soak for ten to fifteen minutes or so and can turn it on and drive it all day.
I tend to agree that it seems like a connector that isn't making a good connection until it gets some heat in it.

 

All of that,,, in 10hrs? Amazing Man!

 

Hey, i bought jags, i haven't had a functioning road car in four years. I had to do some errands haha.

 

You really need to have ‘the staff’ do those.