So I'm stumped. There are more things for me to check but the easy stuff is all done and frankly I'm getting tired. It's been an awesome truck, I've owned it now for 6 years and have add a long list of enhancements (locking OEM rear diff, ARB front bumper, winch, radar cruise control, NAV, etc.), but it's been bricked in my driveway for two months and I'm running out of ideas.

I pulled a persistent P0504 error at first. The splices looked fine to me in the sill (they weren't but I had found the wrong splice) so I pulled the CJB. And then life got busy, the CJB is not a fast thing to remove and replace, and weeks went by. This weekend I replaced the CJB (it was pristine) and found the Fuse 66 splice (the two red wires going to one in the sill, sealed with blue tape. Seriously, Land Rover, blue tape with zero sealant in a water prone spot?).

But now I'm dead in the water. Truck starts but is immobilized due to ABS lock. I have transmission and 'brake' errors on the dash and the codes are communication codes. P0504 still shows up sometimes but my persistent codes are U0104 (lost com with speed control), U0416 invalid data from vehicle dynamics control module, and a similar transfer case comms error.

With so little information on the codes, I'm not sure where to start. I don't see a convenient splice of the high speed CAN lines in the sill or where I have been messing with wiring. Looking at wiring diagrams CAN splice SJ720 look like a possible culprit but I have no idea where to start looking for that.

I had hoped perhaps I had messed up the steering angle sensor calibration but recalibrating it (twice) did not do anything.

For right now... I need to take a break from it. If I can triangulate connection locations, I can check wire continuity but I probably have only a few weeks left until I give up and have it removed. A sad end but... the family is getting tired of the large off-road ornament in the driveway.

 

Ok I have some fight left in me still. Some new data and some reasoned early thoughts:
1. I checked resistance on the CAN High lines across pins 6 and 14, and the resistance to say the least is "not to spec", and it varies with the meter scale, so this tells me I have a partial connection or corrosion.
2. The systems that have comm issues are 1. speed control, 2. transfer case, and 3. ABS. But I think the speed control one is spurious, I've had speed control comms issues for ages and it's never impacted cruise control (admittedly I'm using a RRS based adaptive cruise system) or any other system, so I'm ignoring that. If I focus only on the transfer case and the ABS systems, that narrows the suspect lines significantly. Specifically, I need to check C1854 on the transfer box control module to C2365 connector. That one line would take out both transfer case and ABS, according to page 183 of the LR3 wiring diagrams. Now I just need to find out where those are...

Edit: looks like C1854 is behind the battery as is C2365... perhaps as the truck sat for 2 months I had water hit the transfer case module... a common issue I realize.

 

Yeah, you could be onto something. That is a hot spot for issues. One LR3 I came across did not have the battery vented properly and the transfer case connection was ate up something horrible. A lot of the plastic was gone and there was tons of corrosion.

 

I had some corrosion in the transfer case connector pins, I cleaned that up but no improvement. My P0504 errors keep popping up, even though the bad splice is fixed. If anyone has a map of connector layouts that might help me.

 

I know it is for an LR4 but it is the best I have.

My thoughts on you situation:

1. What was the ohms resistance in the ODB socket?

2. More than one bad wire. The the speed control module is up stream of the ABS, Transfer case, transmission module and the engine control module. You say the it starts so the engine control module works, but will not move so the wires to the engine control module seem to be fine. Which would indicate that everything upstream of it is fine also (maybe). Also you said there was an issue with the parking brake. The parking brake module and air suspension modules are upstream of the speed control module and the engine control module. The center console switch pack and restraint control module are between the speed control and the parking brake modules.

3. Bad instrument cluster. since it is the "clearing house" of CAN BUS,. The modules that are failing are not consistent with a single broken wire in the CAN BUS (as far as I can tell) it may be worth looking at the connectors on the IC.

Just my thoughts
Jeff

 

Fixed it.

Thank you, everyone, I appreciate the ideas you all had. In the end, I think I was dealing with a triple failure: 1. brake light power wire splice had corroded, 2. transfer case module connectors had corroded, and 3. my non-OEM brake switch with under 1,000 miles failed.

After having fixed the red wire / blue tape splice in the door sill, I was still pulling weird CAN resistance values. Pins 6 and 14 in the OBD-II port had showed variable resistance across measuring ranges (which is strange and points to corrosion on connectors). So... I took out the transfer case module and cleaned the pins thoroughly.

With the pins cleaned, this morning my resistance on pins 6 and 14 read 60 ohms, which is exactly what it should read. And yet, I still had the errors on the dash and an immobile truck.

Before the auto parts store closed this evening, on really a whim -- because the old brake switch had less than 1,000 miles -- I bought another one.

And bam.... every warning vanished as soon as I installed the new switch.

I'm still slightly in disbelief but hey... I will take the win for now.

Thanks everyone, these forums are invaluable.

 

Wow, that truck is out to give you hell. Glad you figured it out!