Hello everyone! I'm looking for help troubleshooting an electrical problem on my lr3. I have been a land rover owner for just over a year now and have so far enjoyed the experience. It is my daily driver.

Things to note before I get into the symptoms:

1. I have both the GAP IID tool and the RSW software
2. I have replaced the cowl and built a little roof/cover for the opening that could let water into vehicle.
3. Replaced suspension air compressor and front air bags
4. Relaced an o2 sensor.
5. I have a bad parking brake. I heard the gear strip and have removed the fuse for it. Been driving for months without issue.
6. Battery is less than 2 months old - haven't had it load tested yet.
7. LR3 is US left hand drive with 4.4 V8

History of symptoms -

1. Instrument cluster started intermittently going out while driving. It would always start with the fuel gauge being dead. Then all gauges and lights and lcd screen would go dead. Sometimes a bump would bring it back. Sometimes hitting the dash would bring it back. Seems like it would act up more often when it was hot. I drove around like this for a few weeks until I got a new symptom.
2. In the afternoon sun the car cranked up fine. Then I lost suspension and dumped all the air, then one by one systems went offline and displayed in the lcd as faults. The hazards came on by themselves, the door locks operated by themselves, AC turned off, and all of the lights on the cluster went on. I turned off ignition and tried to restart but she wouldn't crank. After waiting and multiple attempts I was able to limp home with flashers on by themselves.
3. Over the next few days it would drive and operate fine and sometimes lose power to cluster but didn't leave me stranded.
4. The next time it acted up and lighting up like a christmas tree I unplugged the battery and that seemed to clear the issues up.
5. Over the next few days I had to unplug the battery more often to clear the issues until that trick finally stopped working altogether.
6. The instrument cluster had all the bells and whistles going off, no suspension, limited gears, a big F on the screen. Would still start.

Things I've done -
I bought a used cluster online from someone stating it was in operating condition and roughly same mileage as mine. I bought the gap II tool and fastlane service to program the used replacement cluster. The gap tool could not read the CCF file from the original cluster. It also had problem reading codes and could not reset codes. Tech support concluded there was an issue on the High Speed CAN Bus preventing proper communication.

I sent my original cluster into a shop that specializes in cluster repair. Still no change in symptoms. Now has developed into not even cranking. No crank, No start. Christmas tree.

I have replaced the brake light switch with new. Tried starting car with tail lights removed. Checked all the bulbs. Probed the power to the brake light switch for battery voltage-seemed fine.

Transfer Case Module (TCM) looks like it's in great shape. No corrosion at all. I even opened it up just in case and it looked perfect. I hit the connectors with some DeOxit contact cleaner.

Checked floor for damp or any other signs of corrosion and found nothing.

Checked each fuse

Check wiring for breaks and/or corrosion at passenger door under carpet.

When key goes to position II the instrument cluster lights up like christmas tree. I try again with my other used cluster and get the same results. I realize it won't ever start without being programmed to the car but I think it's safe to say it's not the cluster.

I tested the OBDII port without battery connected to find resistance on the CAN bus. I also attached a pdf of the diagnostic port -
Med speed bus was 60ohm
High speed bus was 33ohm
Voltage on Med bus is 2.35
Voltage on High Speed bus is 0.78 taken at pin 14 (it was .742 at pin 6)

I probed pin 6 and 14 at the OBDII port while jumping the HS bus wires on the TCM ecu. There were two connectors that had HS bus wires. A yellow connector and a blue connector. The reading for the HS bus while both of the TCM connectors were jumped was 36.7ohms. Once I removed the jumper wire from the yellow connector (leaving only the blue connector jumped) the reading went down to 18 ohms. When only the yellow connector was jumped the reading was back to 36.7ohms.

ABS has battery voltage to it's connector.

At this point I'm kind of stabbing in the dark. I don't have any codes except communication codes. And it's pretty much every module on the HS bus.

Sorry for the long post. Any ideas?

 

Check your grounds in the engine bay. No codes whatsoever? What do you mean by communication codes, it would help to know what those are because it seems like some parts of the truck are having trouble communicating with other parts of the truck.

 

Also one on the passenger side wheel well. Thought I had an alternator going out but it was that ground being corroded

 

Will check the grounds and let you know what I find. As soon as I can I will put the actual codes up.

Armyrover, I too am in the CSRA. If you ever need use of a gap tool, it would be nice to see it work at least once. Haha.

I appreciate the help!

 

I bought a Gap tool the same day I picked up my first LR3. It has saved me a ton of money. I appreciate the offer however.

 

Im still suspecting the cluster.

If you have a bunch of modules that are not communicating with the cluster, then that is it.

Good luck