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2002 US G500, 125K miles. It's all original, no aftermarket changes of any type, ever.
It's solid except for twice in the last 6 months the dash goes nuts with warnings and errors. Tonight was the worst.
Randomly the screen indicates SRS, tele aid, display, brake reservoir, malfunctions. The indicator for high beam will randomly flash. The blinkers will randomly work. The AC turns itself on or off. The top row of buttons on the center console will light up or be dark. The windows randomly won't work. It randomly didn't know how many miles to display on the odometer. Steering wheel controls wouldn't work.
Engine and brakes and exterior lights all work fine so I was able to get home safely from twenty miles away.
Sounds like possibly a bad ground? Bad SAM? Voltage regulator?
2002 US G500, 125K miles. It's all original, no aftermarket changes of any type, ever.
It's solid except for twice in the last 6 months the dash goes nuts with warnings and errors. Tonight was the worst.
Randomly the screen indicates SRS, tele aid, display, brake reservoir, malfunctions. The indicator for high beam will randomly flash. The blinkers will randomly work. The AC turns itself on or off. The top row of buttons on the center console will light up or be dark. The windows randomly won't work. It randomly didn't know how many miles to display on the odometer. Steering wheel controls wouldn't work.
Engine and brakes and exterior lights all work fine so I was able to get home safely from twenty miles away.
Sounds like possibly a bad ground? Bad SAM? Voltage regulator?
I had something similar. My main battery was loosing energy. I hooked a trickle charger to it and all was well until the next time. I think I will need to replace my battery.
Just went thru this as temps dropped in VA - SRS, mis-firing and tach reading wrong.... new battery solved all but the SRS, which I'll address as I swap the wheel out for a custom rebuilt one.
My 2012 G550 has the same/very similar issue. The previous owner had the truck in storage for a year. The coolant stop warning and a few warning messages were on during the test drive. He replaced a new battery before selling it to me and insisted the truck requires more frequent driving and then everything should be fine.
I charged the battery at night in my garage to determine if those warning lights had something to do with the low battery level. However, after two weeks of daily driving, the truck still has those annoying warning lights from time to time. Even sometimes the truck starts without warning lights in the morning, it could have 1 to 6 warning lights and messages during the drive. It's frustrating because every time I thought the truck was finally ok, it just gave me 1 to 6 warning lights for unknown reasons and they could go off automatically.
The worst case is that there was one time when all 6 warning lights came up during a late-night drive in the remote countryside, not only did the dash beep every few seconds to pop up a warning light but also the headlights were turned off for about 2 minutes!!! It happened on a rainy day on rural country roads where no street lights at all.
My 6 warning lights/messages are (1) Display Malfunction Service Required, (2) LOW/HIGH Transfer Case Service Required, (3) Electronic Brake Force Distribution Service Required, (4) Coolant Stop Turn Engine Off, (5) ABS, ESP Inoperative See Owner's Manual, and (6) Speed-tronic Inoperative.
Besides, the outdoor thermostat display is about 5 degrees Celsius higher than the actual outdoor temperature. I'm not sure if these are related.
Please shed some light on this haunting electrical problem. Much appreciated.
Get a battery - it's very likely the root cause.....
The seller claimed he just replaced the battery 2 weeks ago, right before selling to me, just to make those warning lights go off.
However, warning lights are still on and off daily.
It is possible he did - and maybe the ground wire to frame is corroded..... ? Had that happen on our landcruiser - on the Merc it's less obvious visually.
My previous photos posted above demonstrate so so-called "dashboard like a Christmas tree." Here are the latest codes I've got from the G550 while my technicians have torn down many interior panels and worked for WEEKS without a clue.
Is it really that challenging to source the root of such an electrical gremlin? Any insights, advice, comments are much appreciated.
What is your battery voltage currently at when the G is off? Make sure it is the correct battery in there also.
What is your system voltage when ignition is on but motor is off? What is your system voltage when your engine is running?
Everything here points to a bad power source, so that could be battery, alternator regulator, or bad grounds. There is a very low chance that all of these separate modules are failing all at once without a common source problem.
Fixed issue on the g550 I was working on!! Worth checking out.
Fixed!! So I had a CAN scope connected and would get a bad signal when moving the wiring behind the center console around behind the climate controls. I pulled the radio out and got the signal to stop failing. I could see a stud or bolt that the dash frame is connected to behind the radio...the harness is routed around the stud. So I followed the harness to where it would be next to the stud if the radio were installed...opened the tape and found a small pin hole that had been running on the stud at times shorting the CAN wiring and causing all kinds of warnings and light flickers and bs.. so I wrapped the wire and the harness, and put felt taped around the stud and routed the wiring to be free of binding. The signal no longer failed and the vehicle is functioning properly. Took me a while to get back and update this, but figured I'd better since I had access to a CAN PICO scope. So even if that's not your spot, try looking for a shorted can wire.. they're all red brown or red and brown, usually wrapped together, if you don't know you can Google. Good luck hope it helps.
My local MB dealership said they found the body wiring harness melted at ground points under the hood, and thus
recommend replacing the front SAM quoted for $1,899 and the body wiring harness quoted for $20,837.
The service advisor didn't quote for labour as the figure had gone through the roof.
The truck still drives beautifully with random warning lights on all over the dashboard.
The jaw-dropping quote is beyond my knowledge. Any recommendations?
OP here and I think the wiring behind the radio is a big clue, thanks to Redroe for posting that
On mine, the issue only shows up after I hand wash it and the issue goes away after it sits in the garage a few days. This leads me to believe it's entirely due to water ingress somewhere and it's likely a loose or corroded ground or SAM behind the dash that only gets wet when the truck is blasted with water. It doesn't happen in the rain, however.
Also the one I was working on had a leak at the wiper arms.i had thought it was the problem with the electrical and figures it was getting on the front Sam but no it just went on the floor. Then the water sneaks in past the wiper arms and somehow drips right into the ventilation tubes and fills them up before even getting under the carpet. Then backs up in the vents either to the blower motor or out to weird places. The other spot is the drain in the big air box outside can clog and then put the water in the blower housing also. Reseal those wiper arms in case and clean the drain in the big box under hood.
I wanted to clarify about my previous posts, the symptoms were lights on the cluster coming on and off and random times, warnings for SRS and the brake and park warnings, and the brights on light and others, the whole cluster would also go completely dark sometimes. But always just for a quick flash and then be normal again. The owner described it like Christmas tree. And as far as the short...
The CAN wiring that had a short against the metal stud was behind the radio, but it could be a CAN wire at any point from that CAN bus, shorting, that would cause the problem. Hope everyone finds their gremlins...and yes it can take quite some time for techs to find a gremlin, especially without out a good CAN scope, and also between jobs that actually produce hours for a shop now, it's very difficult for a tech to leave a problem car like that, but even more difficult when you know you'll spend more time then it pays..yet I still wanna keep hunting for the problem.
06-24-2023, 10:20 PM
