ESP malfunction and check engine resolved (long story)
04-02-2014, 01:03 AM
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2004 E500 4Matic
ESP malfunction and check engine resolved (long story)
I've learned a lot of useful information about maintaining my 2004 E500 4-matic on this site, so I thought I'd share my most recent experience.
Last week on my way to work, less than 1 mile from home the ESP malfunction visit workshop message appeared and the throttle was unresponsive. I coasted to the side of the road and noticed the gas pedal did not respond. The engine still ran and idled fine so I thought it went into limp home mode. So I drove back home on the side of the road at about 5mph. While driving slowly I checked if anything else wasn't working. I noticed the check engine light was on and also the speedtronic cruise control "was not available".
Parked it in the garage and took my truck to work. After work, connected my SDS and got the folllowing messages, check A7/3n1 SBC Control unit, check N49 steering angle sensor, and C151B fault in CAN communication with engine control module. After a lot of online searching it appeared that in several cases the steering angle sensor caused similar scenarios so I ordered one (local dealer didn't have one) and installed it very easily. After clearing the codes with STAR still had the ESP malfunction and C151B code. Further investigation following the very good DAS/XENTRY troubleshooting sequence, showed the M16/6m1 throttle valve actuator was a problem, so checked the resistance between pins 3 and 6 as directed and found a short. Reviewed more online stories and it looked like the throttle body was a fairly common problem. So I removed the air intake and rubber elbow to inspect the throttle body. When I looked down I saw all the wires going to the TB connector were BARE COPPER! (see attached picture) I thought about it for a second and immediately knew this was the problem. At first I thought they may have been melted, but after looking closer it looks like they were chewed by little teeth rodent style and there were dried leaves and other debris that shouldn't be there.
The copper wires were still intact and only the insulation was removed so I temporarily taped them up until I can buy or make a new harness with connector (the locking tabs broke off during removal).
I was elated to find and fix the problem quickly, but irritated with the little rodent that caused this. BTW, this is a daily driver and hasn't been sitting for a while. It's normally in the garage, only parked outside occasionally.... I don't expect this is a common occurrence but may help someone troubleshoot corroded wires or other non-typical component failures.
Anyway, sorry for the long story, but I wanted to share this experience. I probably didn't need the steering sensor, should have checked the throttle valve first but I didn't think that would cause the ESP malfunction.
Anyone want to trade a probably good steering angle sensor for a throttle body actuator connector harness with at least a foot of wire? Just kidding, but I am looking for that connector.
Last week on my way to work, less than 1 mile from home the ESP malfunction visit workshop message appeared and the throttle was unresponsive. I coasted to the side of the road and noticed the gas pedal did not respond. The engine still ran and idled fine so I thought it went into limp home mode. So I drove back home on the side of the road at about 5mph. While driving slowly I checked if anything else wasn't working. I noticed the check engine light was on and also the speedtronic cruise control "was not available".
Parked it in the garage and took my truck to work. After work, connected my SDS and got the folllowing messages, check A7/3n1 SBC Control unit, check N49 steering angle sensor, and C151B fault in CAN communication with engine control module. After a lot of online searching it appeared that in several cases the steering angle sensor caused similar scenarios so I ordered one (local dealer didn't have one) and installed it very easily. After clearing the codes with STAR still had the ESP malfunction and C151B code. Further investigation following the very good DAS/XENTRY troubleshooting sequence, showed the M16/6m1 throttle valve actuator was a problem, so checked the resistance between pins 3 and 6 as directed and found a short. Reviewed more online stories and it looked like the throttle body was a fairly common problem. So I removed the air intake and rubber elbow to inspect the throttle body. When I looked down I saw all the wires going to the TB connector were BARE COPPER! (see attached picture) I thought about it for a second and immediately knew this was the problem. At first I thought they may have been melted, but after looking closer it looks like they were chewed by little teeth rodent style and there were dried leaves and other debris that shouldn't be there.
The copper wires were still intact and only the insulation was removed so I temporarily taped them up until I can buy or make a new harness with connector (the locking tabs broke off during removal).
I was elated to find and fix the problem quickly, but irritated with the little rodent that caused this. BTW, this is a daily driver and hasn't been sitting for a while. It's normally in the garage, only parked outside occasionally.... I don't expect this is a common occurrence but may help someone troubleshoot corroded wires or other non-typical component failures.
Anyway, sorry for the long story, but I wanted to share this experience. I probably didn't need the steering sensor, should have checked the throttle valve first but I didn't think that would cause the ESP malfunction.
Anyone want to trade a probably good steering angle sensor for a throttle body actuator connector harness with at least a foot of wire? Just kidding, but I am looking for that connector.
