New battery, apparently good cables.

I get the PBF/Cruise Not Available every couple days if I let the electric park brake set itself. If I hold the lever down while removing the key, I only get it maybe once a week. When I get the fault, it's extremely hard to get it to clear. Disconnect battery, touch ground cable to +, all the tricks - it's not working anymore. If I leave the battery disconnected overnight, that seems to do the trick.

So, what's the deal? I have a set of PB pads which I intend to put on, because my mechanic said they were worn. Will that fix it, or do I have a bad module?

Oh, one more thing - this problem is nonexistent during the summer. When it starts to get cold (maybe the wet has something to do with it too - I live in the Pacific Northwest, and cold=wet up here), the park brake fault is incessant.

Thanks,

Ken

 

Battery getting tired?

Or maybe a poor power/gnd connection?

 

Actuator, cables, calipers. Inspection required.

 

Sorry, I tried to keep from going down the same-old troubleshooting route in my setup for the question...

Battery is new.
Cables are probably good.

 

I feel like this is moisture-related, given that the problem never happens in the summer and is incessant during our wet winters. So... something that is exposed to the weather, maybe under the car? Which leads me to motor(s) and wiring under there as being a potential culprit.

I keep wheel-chocks in the trunk now. What a PITA.

Ken

 

Um, Ken, is this a drinking game? We take a shot every time you provide a clue? Good thing I'm not driving tonight...

I've highlighted the statements that grabbed my attention.

1) First, please note you're not getting just a parking brake fault. You're also getting a cruise control fault.

2) Then you mentioned all is well if you leave the battery disconnected. That would point towards something draining the battery overnight.

3) The cold? That's tough on a battery, even a new one in good condition. I don't think it's the damp causing trouble, but the low temperature.

To experiment, you could leave the battery connected and hook up an automatic battery charger overnight. See if the car now behaves itself when starting out fully charged. That would help you determine if you should investigate a drain on the battery.

How to test for a quiescent drain:

https://www.jaguarforums.com/forum/s...-drain-123535/


I created this scorecard thread to determine if the battery (or a battery discharge condition) is responsible for the typical handbrake/cruise control faults commonly seen on 2003+ cars. It also includes some troubleshooting tips and links to other threads on the same subject:

https://www.jaguarforums.com/forum/s...attery-193787/

 

tl;dr - I'm checking ALL of the material you have posted, kr98664. No stone will be unturned.

Well, EVERY time I've ever gotten the park brake fault, it's accompanied by "cruise not available", so I assumed they were related or controlled by the same module. I'm not trying to be coy, just going through the steps here

I don't see why leaving the battery disconnected for more than 10 minutes would help (even though it did). If the battery wasn't charged enough to run the motor when I disconnected it for 10 minutes, why would it be charged enough in the morning after being disconnected for 10 hours? My guess at the time was that whatever EEPROM pin was being discharged by leaving the battery disconnected just needed longer. My second guess was that something was wet and needed drying out. I'm prepared for both of those assumptions to be wrong!

Also, I wouldn't call the Seattle area "cold". It's certainly not Midwest-cold... The error popped today in the parking lot of a KFC (don't judge my lunch habits), and it was 50F and raining.

I brought up the wet, because I have had (and continue to have) other problems related to water leaks.

Ok, so it let me take a step back and evaluate for battery/discharge/charging problems, yet again. I want to 100% rule that out, since it's always the very first thing that everyone suggests

Ken

 

My hunch is the two faults are related not by a common module, but by a common input. In this case, the common input is low voltage.

Excellent question! It has to do with how an automotive battery will self-recover to some extent after a heavy discharge. Have you ever run a battery down on a car that won't start? Give up, walk away, and then come back after fifteen minutes or so. After this little rest, the battery mysteriously regains some power. Not a lot, but maybe enough for the starter to make a few more turns. This phenomenon is called self-recovery.

It has to do with the chemical reaction as battery acid leaches in and out of the thick internal plates. Run a battery down quickly, and you'll only utilize the "charged" acid near the surface of each plate. So you end up with a "discharged" surface but a "charged" core in each plate. When a partially discharged battery sits, the charged acid from the core migrates out to the surface and becomes available again. This leaching action is what causes the voltage to recover somewhat.


This commonly gets suggested because it commonly fixes the problem.

 

+1

it's nearly always the battery.

Or the connections of power / ground somewhere - usually at the battery.

If this one is not new AND also just now been fully charged then it's #1 suspect.

 

Well, it's a new battery. I replaced it last year at your urging, JagV8j

I'm checking voltages now:

After sitting parked all day in the parking garage: 12.5v
After the 33 mile drive home: 12.6v

I'll check it in the morning before I start it. It's not on a charger, so I'll get an idea about parasitic drain. I'll put it on the charger Saturday (I have a CTEK), and will try again after it's fully charged.

BTW - it's a Duralast Platinum H8-AGM, from Autozone. It's rated for 900CCA, and it's less than a year old. My car sat 10 days between Dec 22 and Jan 2. It had begun acting up before that (when it started to get cold), but has been a real pain since the beginning of the year...

Ken

 

Voltage this morning was 12.39. I decided to work from home and charge it, so the CTEK is hooked up.

12.6 to 12.39 overnight doesn't seem like much of a drop, but I guess I'll know what "fully charged" looks like in a few hours.

Ken

 

12.86v directly off charger - which was already in float mode. 4.5 hours to get there.

Battery is disconnected for 10 minutes to see if the module resets and will let me do the EPB calibration.

::crossedfingers

Ken

 

Sounds like either you don't drive enough (e.g. short commutes) or have a drain

 

Actually, that is a pretty good drop. The total variation from fully charged to discharged is only about 0.8V. You recorded a 0.21V drop, which is over 25% of the total range. Here's one chart with the values:


https://www.emarineinc.com/Batteries-Maintenance-101


Put another way, per that chart, your battery charge dropped overnight from approximately 92% to 72%. Personally, I'm not a big fan of determining state of charge by measuring voltage (too many variables), but it can provide a useful rough estimate.

That's why I suggested keeping the battery on a charger every night for a week or so, as a test. Start with the fault cleared, and there should be no need to disconnect the battery. Drive the car every day and see what happens, knowing the battery is fully charged.

If the fault stays away, then you know it is caused by low voltage before engine start, as so many others have experienced. If so, then your next step will be to determine if the low voltage is caused by a charging system problem, a drain running down the battery overnight, a suspect battery that won't hold a charge, or a combination thereof.

No whining that it can't be the battery because it's only a year old. I'm not very impressed with the WillItLast, I mean Duralast line of products from Autozone. Yes, they are made with the finest grade of Chinesium from the Fling Dung factory, but some of their starters and alternators are just dismal quality, for example. No personal experience with the brand, only anecdotal reports from other forums. YMMV.

 

Well, I took it off the charger and drove myself and the wife 34 miles in to Seattle for a night out. Stopped the car to have it valet parked, switched over to the valet key for them (so I had to shut off the car), and let them have it. A few minutes later, they came and found me inside stating they were "having trouble with the parking brake". After they started the car it park brake faulted... I was super pissed at the car, and forgot to take a voltage reading of the battery. Fortunately, I've got plenty of practice "hotwiring" the EPB and keep my specially made wire under the boot floor (cut from a lamp cord I bought at a grocery store once night late, when the car stranded me about a mile away in the dead of night, and I had to hotwire the park brake).

So - the drive in to Seattle wasn't enough to recover the charge drop from starting the battery? Battery is on its way out, or there is a charging system problem, eh?

Dammit.

 

Or a drain.

 

A drain while I'm driving that is larger than what the charging system can recover.

There is probably another drain which is sapping the battery overnight. Or it's a bad battery refusing to take or hold a charge.

At least we're in the realm of something I can more easily troubleshoot.

 

When did Jack In The Box get valet parking? Is that new?




34 miles is plenty of time to top off the battery, especially if it had just been charged before you left. The more likely scenario is the charging system is not up to snuff, and you slowly ran the battery down without realizing it, but it wasn't bad enough to turn on the little battery warning light. This is just a guess, though. Also, in certain cases of total alternator failure, the warning light never comes on. The alternator's internal module has to still be functioning to send out the command to turn on the warning light. It's a catch-22 if it fails totally.

It's time to run some more diagnostics. I have a little cheap voltmeter that plugs into the cigarette lighter. It even has an alarm if the voltage drops below a certain level. I'd suggest something like that so you can keep an eye on the charging voltage while driving. Generally you want to see around 13.5VDC while driving.

You can also read the charging voltage at the battery with a regular voltmeter, but that doesn't actually capture what is happening when driving, in case you have an intermittent fault.

Don't forget to start with a fully charged battery for any electrical troubleshooting.

 

In the interim have you looked at the mechanical side of the system as suggested way up top.

 

Good suggestion. I was concentrating on the electrical side because I'm lazy.

The latest incident might point to an alternator not charging properly, and the battery ran down enough to cause a repeat at the next start (by the valet). Then again, it could point to a mechanical fault, too. But as lazy as I am, I'd much prefer to spend five minutes with a voltmeter checking out the charging system before crawling around looking at cables, etc.

One more thought. How is the cruise control fault tied to the parking brake fault? It is well documented in the forum that the two faults often appear together, and the battery (either defective or partially discharged) seems to be the primary culprit for both. But is it possible for a mechanical fault with the parking brake system to also trigger a cruise control fault?

I'm just trying to get some background to help future troubleshooting. The next time somebody mentions a parking brake fault, maybe the presence or lack of a cruise control fault would help direct where to look. In other words, if I'm extrapolating correctly, a parking brake fault by itself is probably mechanical. Both faults at the same time is probably electrical. Any thoughts?