The rear disks are fine, barely worn at all. I do have a set of EPB pads that I've been procrastinating on installing :(

I had the same problem over and over...I checked all electrical and found nothing...I finally replaced the rear pads with top of the line pads and lubed everything that moves really good and have not had that fault again....there was some uneven wear between the two sides...I found out the hard way of do not turn the car off in park with that code on unless you are in a spot you wish to be..as long as that fault code is present no shifting out of park....luckily it reset on the 3rd startup before too many horn honks came my way at the green light...I was just trying to do a reset like I always did...turn car off and restart and code disappears...anyway that is what fixed mine so i must have done something right...If there is one thing about my car I am a little disappointed with is the electric park brake system, but not enough to talk bad about it in any way overall

It may be that all the sticky stuff stopping the movement required by the EPB is looser as it's warmer and if so that points to the real problem.

40A would be, I suspect, far too much for the battery in our cars.

13V would include surface charge on our cars, I believe, so is not a good voltage to aim for.

Your & my STR have a smart charge system for lead acid batteries and it seems to work well. When it doesn't it seems to indicate a fault - wrong battery type, bad connections, failing battery, etc.

Bumpity bump, you still there, Ken?

The test of the ignition switch, detailed in post #95? It will take all of five minutes, if even that, and either fix the problem or shut me up. You can't lose!

The cold/wet weather correlation? Still wondering if that's related to the electrical load from the use of seat heaters and defrost, and not the actual weather conditions.

When I changed my rear rotors and EPB pads a few months back I also had some issues with the procedure for full retraction. My battery is getting long in the tooth now so I added the help of a jump from my truck and that solved the situation. The battery isn't quite bad enough yet to require replacement but it wasn't up to snuff for that procedure. I'm guessing this will be it's last year. I park the car for the winter so probably during that time I'll be shopping for a new one.

Maybe your problems would all go away with a new battery?

This happened earlier in the year with my truck. It charge fine but lost it's verve after about a week. I thought I had a parasitic loss or possibly a fading alternator but it was just the battery going south and it was just out of the full replacement warranty of 3 years so I got prorated to to about 1/2. The next one is going to fail just before the deadline ... I promise! :icon_naughty:

Ken, are you still out there? Any updates for us, or has this become yet another unresolved thread?...

Maybe a take the help and run or a give up situation I guess

It's Park Brake Fault season again!

Yes, I've tested the ignition switch and it's fine. I had zero problems all year once the temps warmed up and the rain eased up. Last week, it started again in earnest.

The battery, as you know, is now only a year old. I installed a volt/amp meter in the trunk, wired to the battery for voltage and a hall-effect sensor around the ground cable for amps. I did the "sleep" test many months back - couple times to make sure - and the quiescent current is right down where it ought to be.

Since this is a 100% seasonal problem, I can't really work on it or provoke reproductions of the issue until it gets cold/wet.

Tonight, I couldn't get the damn module to reset by disconnecting the battery, so my EPB is non-functional right now. So, thus starts the rule-out process again:

1. Cables: clean and lubricate liberally.
2. Motor: Largely inaccessible, but it works 100% fine - every time during the summer/warm months.
3. Battery: Battery is new. N/A
4. Module: I pulled the module out last winter and inspected it. All the discreet components are fine. There are no burnt traces. ICs could still be bad but - again - the brake worked 100% fine all summer, so I'm less inclined to think it's the module.
5. Sensor ghosting: I definitely have a leak at the bottom of the windshield, at the cowl. There is a BIG harness connector down there at the top of the rear of the engine, with lots of action going through it. If that thing gets water in it, lots of sensors are going to be shorted to ground. This will play hell with all the modules which are listening to those sensors. Many of the modules won't go to sleep if the sense input is low, which can cause battery drain.
6. Other battery drain/charging issues: Today, the battery was definitely low; the car sat for over a week while I've been off work for Christmas - but (there's always a "but"), it started up in the morning without drama and I drove to work. Parked inside, out of the wet all day and when I came back to it in the evening - PB Fault. With the key on, no A/C, no radio, no lights, no seat heaters - just whatever the computers are drawing, and the intercooler pump, netted ~16A drain, and the voltage drop took the system below 12V. It's possible the large load from the cold-weather accessories is out-competing the charging current. That didn't seem to be the case last year - the alternator was keeping up just fine based on my measurements.

So, tonight I'm going to try and get the damned module to reset and clear the PB Fault and then lube up everything that I can see under there that participates in the EPB.

Ken

I don't remember what the reading was, exactly, but the dV was less than 0.5v. I tested it several months ago, though, so it's a good idea to get a new baseline to make sure it's still not a problem.

The underside of my car is remarkably clean for how wet it is here for 6mo a year. I went under there and located the cables and the cam actuators and lubed everything up nicely. Battery is disconnected and on a charger to top it up nicely overnight and give the fracking computer a chance to reset to a mode where I can actually connect to the accessory modules with my scan tool.

I'm bringing test equipment with me to work, so I can do some more troubleshooting at lunch time (indoors, out of the weather, and not so cold!) - I'll retest the ignition switch then.

Ken

Ken, Ken, Ken,

Hope you've got your seatbelt on. You may regret ever coming back here...

I'm busy at work, so can't reread the entire thread right now. A few general questions for now. Please forgive me if some of these are repeats:

1) Did you see these two recent threads? Could your situation be related?

https://www.jaguarforums.com/forum/s...-maybe-211809/

https://www.jaguarforums.com/forum/s...around-211812/


2) What kind of scanner do you have? Is it able to read any Jaguar-specific codes, such as "key in circuit failure" as mentioned in the threads above?

3) What would happen if you disconnected the cables from the actuator? Would this let the actuator drive back and forth, and hopefully satisfy the feedback, even if the brakes weren't physically being applied? This might help isolate if you've got a mechanical issue or an electrical/command/feedback issue.

4) Have you ever checked for AC ripple from the alternator? If so, was this done with a multimeter or an oscilloscope? The reason I ask is a scope will display spikes that a multimeter may filter out.

5) Re: Cold/wet weather only fault - Have you tried not using the seat heaters, rear defroster, etc.? Just trying to think of electrical loads that are only present during winter weather.


Of course, we are at a disadvantage because we are both coneheads. (This is an aviation term for electronic techs). To a conehead, all problems are electrical in nature. Sometimes, for chronic problems, we need a knuckle-dragger or mouth-breather (both terms for general mechanics) to actually figure out the fault isn't electrical at all, but mechanical in nature.

Update - after a nice full charge, and the battering being disconnected all night, it still registered PB fault this morning. That hasn't happened before.

1) I'll experiment with the loose/sloppy ignition cylinder idea. I have some electrical tape (conehead).

2) My scanner is a Foxwell, and it can read the special Jag codes. However, when the car gets into this state, the scanner refuses to connect to the ECU in anything other than vanilla OBD2 ways, which means no special Jag-only codes for me, and I can't connect to the accessory modules at ALL. It's very frustrating.

3) I'm not sure, but this does make me think of something. I noticed the brake was not fully un-set when I was under the car last night. I'm going to go hotwire the motor and drive it back and forth a few times to get the lube distributed. I bet that, after fully setting, then fully un-setting the brake that it'll be in a happier state as far as command/feedback are concerned.

4) I checked with my meter set to AC volts. It's been a while since I did that, so I'll need to get a new baseline.

5) My drive to work is long enough that tall that stuff is only on for the first 1/3 or less of the drive. The next 40-45 minutes are driven with: headlights if it's a gray enough day, wipers because it's raining, and that's it. Seat heater has done its job, and the rear window is clear before I even leave my neighborhood (I won't drive with it fogged up). So - not specifically, but effectively "yes".

I'll check the motor draw and resistance directly while hotwiring it tonight. I'm getting close to just fabricating a test harness/splice for the EPB module, so I can datalog EVERY pin :/

Rechecked voltage drop at F3: w/Seat Heaters, Defrost = 191mV, without = 141mV

Seems reasonable to me.

I forgot how hard it is to reach the alternator V+, so I'm going to delay that test to the weekend (I'll have the belly pan off to change the oil anyway).

Checked the ignition cylinder play - opened the door with key in, got bing-bing-bing, then moved the key all around and in and out to no effect. There's a lot of play, but it didn't seem to matter.

After winding the EPB in and out a couple of times, the module didn't trigger a calibration cycle. So much for that theory.

I need to replace the EPB pads, still. I'll do that this weekend as well. If that fixes it, I'm going to seriously reexamine my life choices.

Ken

The recalcitrant scanner seems very odd to me. To make sure I understand correctly, you can read all of the modules except when the PB fault is active? Makes you go, "Hmmmm." Is that a fault originating with the data bus? Or is the data bus reacting to a fault elsewhere?

For the AC ripple test, do you have access to an oscilloscope? Testing with a multimeter isn't conclusive. Strangely, cheap meters often do a better job of catching voltage spikes. Meters are expecting a smooth AC sine wave and spendier meters smooth out those spikes. Best of all is an oscilloscope to view spikes.

Back to those actuator cables - Have they ever been replaced? Might be worthwhile if contaminated and they can't be disassembled for cleaning.

Correct, when the PB fault is active my scanner won't talk to the accessory modules. Not sure how to test if it's the data bus or it reacting to the fault. Maybe disconnect the EPB module and reset the ECU?

Sadly, I don't have access to an o-scope. My meter claims to be true RMS (which means it's going to try and smooth out spikes).

I've never replaced the actuator cables. They did seem kind of sloppy/loose but otherwise look OK. No cracks or splits. I cleaned what I could reach of the open ends when I lubricated them.

I wish I knew someone local with an S-Type who would be willing to swap modules with me for a little while to rule that out. They are a little spendy to just get one to try and throw new parts at the problem :(

Ken

More things that make you go, "Hmmm". You had also mentioned you've never changed the cables. I'm not one to just throw parts at a problem, but as persistent as this problem has been, a few well-aimed tosses wouldn't hurt. Congealed/contaminated grease in the cables might explain why the cold weather is a factor. Old cables also wear through the nylon sheath and cause binding. Maybe this extra friction only becomes a problem during cold weather when the battery voltage is slightly down.

Have you had the actuator apart for inspection? Long thread, don't have time to read every bit. Just wondering about the possibility of congealed/contaminated grease in there, too.

My Ford pickup has a well-known issue of cold weather affecting the factory "grease" (more like dialectric compound) inside the ignition switch. All works well in the summer. During cold weather, the switch can act up. The fix is to replace the switch with an updated version that has upgraded grease inside. Not necessarily saying it's your ignition switch, just thinking you may something similar (and weather sensitive) in the parking brake actuator and cables.

Seven pages' worth of troubleshooting, and we still don't know if the problem is electrical, mechanical, or a combination of the two. Sometimes a situation just calls for a stupid, futile gesture. My TheoryDuJour™ is the cables and/or actuator are mechanically binding. I'd lean towards replacing the cables and disassembling the actuator for inspection and a good cleaning. Will that be the fix? Heck if I know, but you gotta try something.

Also, at the start of this thread, you mentioned getting the DSC message at the same time as the PB fault. Are you still getting the DSC message? That would help narrow down if the problem is electrical or mechanical in nature.