[Ayepace]

I'll see tomorrow (I hope they are back from the holidays) if I can drive it in, or if I need a tow.

Thanks for the info!

I recommend taking advantage of the roadside assistance and have it towed in rather than continuing to drive it. You can have it towed to them even if they are closed. Give the tow truck driver a written description of the problem to be included with the FOB drop-off.

 

[Ayepace]

Jaguar filed information about this with the NHTSA. https://static.nhtsa.gov/odi/tsbs/2019/MC-10169910-0001.pdf

It looks like the allow up to 11.2 hours for the repair if the harness needs replacing.

 

[Ayepace]

I don't understand why they didn't make a short adapter to plug in and take the stress off the harness. Do a recall for that and it would be a quicker, cheaper fix for everyone.

 

[Ayepace]

I've seen it done on other vehicles, but it has been a while. Example: A Jeep I had decades ago had issues with wiring to its distributor where it was unsupported and just an "exact" in length to reach. This would cause breaks internal to the wires (you wouldn't see it just by looking at it) that messed with timing signals for the electronic control unit. Jeep issued a TSB. Adapter wiring and supporting fixed it. That Jeep almost went up in flames too for "exact" length wiring to the headlight switch. Too much stress, pulling, and increased resistance there melted the connector causing smoke and loss of external lighting. Fortunately, that's as far as it got before I pulled it apart.

It might depend on what the voltage or amperage going through the wires at the problem connector. I haven't looked it up in the wiring diagrams (yet). If any one wire handles high voltage or current, then I can understand the preference for replacing the whole harness.

 

[Ayepace]

Wiring harness is a replacement if they find broken wires. NHTSA has not requested them to do a recall although I understand a recall was performed in the UK.

Reads like one of the switch assemblies on the steering wheel was found to be faulty too. Possibly the one with the thumb wheel given the wording of "driver side".

 

[Ayepace]

The smaller 12V auxiliary battery was done away with starting in 21MY so that eliminates half the problem. Does it introduce a single point of failure? Well, it only provided 12V for 3 things and the larger 12V battery could work just as well for them. I don't know the reasoning behind putting the small battery in the I-PACE. It had been eliminated from other JLR products, where it had been used to support 12V during the stop part of the ICE stop/start feature, several years before the I-PACE introduction.

Software updates were needed to ensure the charging process worked correctly. Apparently they found situations where it didn't work. It was probably re-worked in eliminating the auxiliary battery, too.

However, we're still at the mercy of the battery not going bad and the relays/contactors involved don't go bad when the requests are made to charge or stop charging.

rcomeau, you got it right per the workshop manual info. The original programming may have been on a different page though.

 

[Ayepace]

You can still brake and stop safely. It just won't have all the brake assist that is has with the 12V (like non-power brakes in the good old simple days).

 

[Ayepace]

I learned to drive in a car without: power brakes, power steering, power seats, power windows, power heated mirrors, heated windscreens (front and rear), air conditioning, air bags, padded steering wheel, shoulder strap in the seat belt, etc,

I was grateful for an engine, 3 speed automatic, 4 tires (whitewalls!!), an AM radio with 1 speaker and they were all connected together and working.

Most drivers are not prepared for a sudden component failure or multiple failures. Not for their cars or the cars next to them. They really need to teach that in driver education classes with specially rigged cars on a closed course.

 

[Ayepace]

Im having the same issue stuck in park and flashing P cannot reverse or drive and can hear a humming noise. JAGUAR assistance here now saying the car needs a new small battery to the front but cannot fix it until four days later! we;ll see what the outcome is. i mentioned to him about the wiring harness that ive read on here but he is adamant its only the battery that need replacing.

Yes it could be only the small battery. That small battery powers the parking lock, the front EPIC (electronics for the front motor) and power brake booster. This shouldn't work if the wiring harness is broken.

If you have the means to apply a 12V battery charger to the small battery, you could test the ability to get it out of park, although I don't recommend driving somewhere and getting stuck there.

 

[Ayepace]

It is probably impossible to repair the connector until the whole thing has been removed from the car due to lack of working room. They might as well replace the harness at that point for a permanent fix.

The picture below from the service bulletin shows a case of the red wire broken as well as others. It isn't just the black wire that can break.

The black wire goes to ground, red (battery + ), white with violet stripe (wake up line), white with blue stripe (park lock position feedback), and brown with white stripe (actuator command line). You can't be colour blind to work on wiring harnesses.

 

[Ayepace]

The wires won't pull loose from the connector. The metal contacts at the ends of wires lock into the plastic connector piece and there is a seal around the wires too to keep out moisture.

Breaking where a wire meets the seal would be a reasonable thing to find since this would be the stress point of a short harness.

These are not high voltage wires and unlikely to cause a spark or anything else that would discolor the severed ends. The small gauge wire breaks and then the insulation breaks.

 

[Ayepace]

People on the UK forum that had the TCU battery go to 0% while in the shop reported that it takes several days and driving to get back to the usual 90%. It may just be a function of time. The TCU gets a constant 12V from the startup battery and should recharge the internal TCU battery from it. They probably had the startup battery disconnected for most of the time that it was in the shop. This would deplete the TCU battery.