Yesterday I started up the LR3 to go run some errands, it had been sitting for about a week since it ran last. The CEL was not on but I could feel the engine running rough, so I pulled codes with the GAP tool:


Initial engine fault codes 1/2

Initial engine fault codes 2/2



I tried clearing all faults to see what would return and even more codes showed up and not limited to the powertrain ECU They seem to be conflicting codes, or just no value errors:





I checked the battery and it was over 12v, and measures 14.8v while the alternator is charging. I don't see any AC voltage so I don't think AC ripple could be an issue. I thought it might still be a bad battery, but the parts store would't take it back under warranty since it passed their testing.

​​​​​​A couple times this summer I had noticed it taking 1-2s to fire, then stumbling for another second during cold starts, but it would always be run fine without any codes. The battery voltage has occasionally dropped to less than 12v (measured with GAP tool) if it has sat for a while. Is this on it's own a definite sign of a bad battery?

 

I would suspect the battery at 11.9v is causing a lot of these faults.

 

I grabbed a new AGM battery but that doesn't seem to be helping. I have also tried a hard reset (jumping pos and neg battery leads for 20min with battery removed) and checked all the ECM related fuses in the battery junction box. Those all have 12v as they should.

I decided to check a random sensor that was giving multiple faults and see if it still has power and ground. I picked the MAF since it's easy to access and confirmed it still 12v on pin 1, and it's grounded at pins 2 and 5. (I also measured 0v on pin 3 and 5v on pin 4, but I don't know what these pins should read normally.)

If I have fault codes on multiple ECUs is it safe to assume the issue is a general power issue or maybe a damaged wire bundle somewhere? Are these vehicles known to get codes on unrelated modules if there is an electrical fault elsewhere?

Any ideas would be greatly appreciated!

 

I don't have experience in this particular issue, but your codes to me say a) battery, b) ECM, c) ECM connector / harness. You've *mostly* I think ruled out a) with the new battery, I say mostly because if your original issue was corrosive buildup on the battery lugs and terminals, just swapping the battery without cleaning the terminals and connections would not necessary improve your situation.

But assuming a) is not the case, the next low hanging fruit I suspect (again, not an expert in this type of issue) is to pull the ECM connector and review it for corrosion and clean it. You can also check it from broken connectors / wires. Also, if you're in Mass, we've had rain this week, look for water intrusion on the connector. IIRC there's some youtube videos on the water / ECM issue.

Best of luck with it.

 

Start broad and simple.

-battery
-alternator
-corroded ground strap (particularly where it connects to the body)
-water in the passenger door sill (wiring loom runs through there)
-water getting in the cowl (it'll fall into the back of the JCB and corrode it)

 

Definitely check out the sill and CJB (it's behind the glove box, lots of youtubes on accessing it) as BlacknGold suggested, that's just a few minutes to check without needing to remove a lot of other stuff.