I finally saved up enough pennies to have my local shop install an OEM differential lock motor and assembly and I couldn't wait to pick up my 2006 HSE this morning. As I'm paying for the service, the advisor says something to the effect that "you've got a great truck there, though you'll have to deal with the suspension warning light at some point." Huh? I'd never seen that light before and as far as I knew, the suspension worked just fine: raising up from access to normal as expected when the driver's door shut after ignition and raising up from normal to off-road the few times I've thought I needed it. Dropping down seemed to be fine as well. When I started the LR3 at the shop's lot, sure enough the little suspension light was on and, to my disappointment, it was a lovely shade of blood red. My hope at that point was that the issue was one of those mysterious ghost problems that can happen when the battery is disconnected from the vehicle for a major service and that it would go away, but as you can guess, it didn't. In fact, I got a bell ding and a "SUSPENSION FAULT - MAX SPEED 30 mph" in the Message Center when I hit that exact velocity, though going faster didn't seem to be prohibited or cause an obvious problem and additional testing today indicated that this warning didn't always occur when accelerating from a stop light, even during a fresh drive cycle. The only thing out of the ordinary was that it did seem to raise up slower than usual, and maybe twice today I saw a "SUSPENSION - VEHICLE RAISING SLOWLY" warning, though that could have been from me playing around too much and depleting the reservoir. Indeed, when I was trying to figure out what was up after sitting in a parking lot and scratching my head, I got a "SUSPENSION WILL RAISE WHEN SYSTEM COOLED" scolding, and from that point on my testing shifted to mere observation rather than an emphasis on wiggling every switch as often as possible in the vain hope that something good would miraculously happen. Lesson learned.

When I got home this afternoon, my IIDTool indicated that there was a "C1A00-54 (AF) Control module - System programming failure - missing calibration ( on 21-02-2022 15:07:05 at 162528 km )" fault triggered yesterday when the shop was working on the differential motor R&R and updating the differential control module software. I keep copies of all my fault scans and not only did this particular fault never pop up in the year I've owned the vehicle, I've never had any suspension system faults. Clearing the faults, starting the truck, and driving around this evening produced the same fault and no others that I think are related.

My guess is that there are three possibilities here: (1) This problem is completely unrelated to any work done on the vehicle yesterday and for some reason only known to a Higher Power, it just happened to rear its ugly head about the time the service was conducted; (2) Something physical happened at the shop (e.g., a wire was accidently pulled, a hole was put into a lift bag, an already dicey sensor was moved ever so slightly out of position) that triggered this suspension issue (not saying this is their fault, only that had it been sitting at home without anyone poking around the light probably wouldn't have been triggered); (3) Something done during the software update or other programming activities caused the system to lose information needed to control the suspension correctly and as a result a fault was thrown.

Any ideas about possible causes and, more importantly, any ideas about how I can address this problem without spending a billion dollars?

Thanks,

Nick in Palm Springs

 

Go through a suspension calibration using the GAP tool and see if that solves it.

My guess is they had it lifted with the wheels unsupported, can cause suspension the calibration to get out of whack and errors.

 

Good idea. I think I understand the GAP tool's instructions on doing a guided sensors calibration (though it's unclear whether I **must** adjust the vehicle baseline height once calibration is done), but before I take the plunge I'll look for a video that walks a first timer through the process (all the ones I've seen so far either use a different tool\software or only discuss height adjustments).

Thanks,

Nick in Palm Springs

 

Raising the truck will not cause issues unless height rods are installed. It's done all the time. Even I do it myself, never an issue. Heck, when off-roading I have had two wheels hanging there like Christmas tree decorations. Just open up the GAP tool, enter guided calibration but then cancel it and follow on-screen instructions. See if that jumps it back into normal operation.

 

No, but having all 4 wheels off the ground, like when on a frame lift, for an extended period of time will.

 

Nope. Heck, mine just had new tires installed and was lifted again this past Sunday. I even have a 1.5" Gap Tool adjustment and no issues and the system was not disabled for the work, it never is. I have never, ever heard that lifting the truck causes issues by default. There is not even anything in the workshop manual or under general procedures, which covers using a lift.

 

If I can extend an Olive branch.....having the truck on a lift shouldn't produce any real fault, but it can confuse the EAS temporarily.

Nick, I would check the height sensors to see if any of them look damaged (wiring, bracket bent, harness unplugged, etc) and then I'd just do a guided calibration. It's super easy. The old school calibration was a little more arduous, but this guided procedure that GAP came out with, is a breeze. You just need a tape measure, maybe a pad and pen to write numbers down....and a beer.

 

It's uncharacteristically cold out here today so I started with the easiest steps:
1) Pulled the ground cable off the battery, waited an hour, and then reconnected. Result: Light still on, C1A00-54 (AF) fault continues to be triggered, operation seems normal.
2) Did a guided calibration (yes, it's easy as pie and takes all of 7 minutes; don't know why I was worried), hit Apply after the 4th wheel, punched Yes to Proceed with Procedure?, and received Operation Successful message. Result: Light still on, C1A00-54 (AF) fault continues to be triggered, operation seems normal.
3) Restarted engine, drove for a little bit, and repeated guided calibration as described in #2. Result: Light still on, C1A00-54 (AF) fault continues to be triggered, operation seems normal.

Tomorrow I'll go under the truck and do a visual inspection of the height sensors. If there's an obvious issue I'll address it. If all looks good I'll try another guided calibration. If that doesn't work I'll try DakotaTravlr's suggestion of "enter guided calibration but then cancel it and follow on-screen instructions", though I'm not quite sure of the point at which I'm supposed to cancel it. If that doesn't work, and if the suspension continues to rise from access to standard\standard to off-road normally and drop to standard or access normally (as it seems to now), I'll just learn to live with the issue. I don't hear the compressor working away endlessly, so maybe this isn't as big of a deal as it seems to me right now.

Thanks for the advice...

Nick in Palm Springs

 

"enter guided calibration but then cancel it and follow on-screen instructions"

At what point do I cancel it (prior to "Accept"? right after start?) and will the instructions at that point be the manual (not guided) method?

Thanks,

Nick

 

When you enter guided, you asked if you are sure? After you click yes, you cancel out. It just reloads the calibration. But since you calibrated, you kind did that. Sounds like you are in tight tolerance or test mode after mentioning all that. Go back at set tolerance to normal.