Nieuwsma

Our 2008 GL320 started fine but the yellow triangle warning was flashing. Car was just idling and a few seconds later the dash warned that ABS and ESP were not working. Then all warning lights turned on and the speedometer went to 160 mph (max on gauge).
I pressed the Start button to turn it off, but no response. I removed the Start button and put in the key, then engine stopped.
That was a hot day, so I tried again today when temp was lower, but same thing happened. This time I got out, closed door and opened hood. The car locked itself and the key did not unlock. I tried the mechanical key and at first it did nothing. Eventually I was able to unlock door, pull the Start button out and put in the key to stop engine.
Vehicle is undrivable at this point.
Where should I start looking for this problem?

Max Blast

So we’re weird electrical symptoms like this are usually a result of water intrusion. Check in your battery compartment under the passenger seat for any water as well as in the spare tire area in the trunk and under your driver seat. I think one of your Sam’s is fried.

Miguk_Saram

Defnitely a rear SAM issue.

Lift the carpet under the spare tire to access the SAM area. The SAM is tucked under the rear fuse box.

Your issue might be as simple as water accumulation UNDER the SAM affecting it's operation, to the SAM itself having been submerged in water and short circuited. With some luck, you may be able to just unplug the SAM, wait a few minutes, then plug it back in. However, you should stil inspect the SAM circuit board for water damage.

If the insulation/foam under the SAM is wet, dry it out as best you can without damaging the insulation, then plug the SAM back in. Allow the area to air dry (don't reinsert the spare tire and let the area breath for a few days). If this results in intermittent operation, unplug the two power cables connected to the SAM, wait a few seconds then plug them back in.

Note: you likely cannot open the tailgate, so you'll have to unlatch the tailgate from the inside.

Nieuwsma

Thank you for your help.

So, I've inspected all the places mentioned above and there is no sign of water penetration now or in the past. All is dry and clean.
I removed the rear SAM and cleaned the contacts and reinstalled. Then I cleared codes and re-read the diagnostic codes. There are now a lot less error codes. The ABS and ESP systems are still disabled.

UCP - Upper control panel
9023 No CAN message was received from control unit N70 (overhead control panel unit).
9024 No CAN message was received from control unit N10/8 (Rear SAM control unit).

ESP Electronic stability program
5026 No CAN message was received from control unit Transmission control.
5102 L6/1 (left front speed sensor): check wheel bearings.
5995 Temperature Service brakes
5132 L6/4 (right rear speed sensor): check wheel bearings
5122 L6/3 (left rear speed sensor) check wheel bearings
5112 L6/2 (right front speed sensor): check wheel bearings
7271 Implausible values from rpm sensors: Front axle
7270 Implausible values from rpm sensors: Rear axle
5399 CAN signal 'Gear selected' from control unit N15/3 (ETC [EGS] control unit) is implausible.
5101 l6/1 (left front speed sensor): Carry out visual inspection.

Rear SAM - Rear signal acquisition and actuation module
Normal

Does this still look like a Rear SAM issue?
Where is the "Upper control panel"?
Any ideas where I should look next?
Thanks for your help!

Nieuwsma

There was a small oil leak dripping oil on serpentine belt, which over time sprayed area by front of engine. I stopped the oil leak and cleaned some of the oil spray off various components. I cleared the error codes and it has been working well ever since.

Sallad

This leak affected your starting issues? wow. Strange find.

DennisG01

I certainly hope your issue is fixed, but I can't fathom how that oil leak would cause those problems. I suspect it was just a coincidence.

Max Blast

coincidence or not, this could possibly have caused your alternator belt to slip enough to where it wasn’t charging the battery thus creating a low voltage situation, which would give you the symptoms you described.