krekavhts
Member
I just thought I would post up a few details I have worked through on my Jetta. It has 337k miles, egr delete, lots of other mods. I bought it a few months back from NH_TDI.
Last Wednesday I went to start the car and nothing. I had some electrical issues with the grounds on the installed PD lift pump and figured my splice job had failed. After diagnosing, it was clearly not a lift pump or air situation.
The symptoms were cranking with only the occasional cough, but no real attempt to start. I investigated anything causing a bad ground to the fuel cutoff solenoid, the functionality of N109 along with all fuses. I found nothing that seemed off.
I ran VagCom and received faults for the G28, Crank Position Engine Speed Sensor and N109 implausible signal at fuel cutoff solenoid. Knowing that wire chaffing was an issue I began to investigate the wire connections along the front of the block.
After initial investigation of the connectors (black for the Cam Position, gray for the Crank/Engine speed) and some jiggling the wires I had my wife come out and crank. Car started immediately. As I was in the middle of brewing beer and the day was getting late, I left the issue for further investigation the next morning.
Next morning the car was back to no attempt to start and throwing the G28 sensor problem. So back to investigating the wiring.
I initially found severe chaffing and exposed copper on the wire loom/main harness side of the Cam Position sensor. Knowing that a problem with this sensor could also cause strange ECU codes, I cleaned the area, applied liquid electrical tape, verified there was no short. The car started right up, ran for 45 minutes through multiple start/stops etc. Pat on my back I fixed the problem.
On my commute to work the next morning I hit a bump in the road and the car died. Pulled car over, stopped, key off, car re-started immediately. I continued my trip and 10 miles later at a stop light, the car died and went back to no attempt to start.
After getting the car in a safe spot I check VagCom and initially saw the G28 code come back. I jiggled the connectors and wires a bit went back, still no start and now VagCom lost all communication for the Engine block. Not Good.
Car towed to office and I dug in further to area's that looked like corrosion might be taking place. It was clear that there was wire damage on the main harness wires coming out of the gray G28 Engine Speed sensor, but no visible damage on the side that actually goes to the sensor.
I began cutting back the sheathing going up the wire loom and found multiple cracks in the signal wires and signs of corrosion on the outer foil. Thinking I had found a short, I reconnected and tried starting, still nothing.
Now on to the sensor side wiring. Everything looked perfect. If I placed a good, Fluke, multimeter on the signal wires (positions 1 and 2) I got a nice, constant 1100ohms, in spec. Now if I jumped from 1 or 2 to the 3rd position I would see very very strange behavior. As you moved the wire about you'd see spikes from 50k ohms down to 3 ohms. Obviously a big problem.
The failure happened right where the wire goes into the gray connector. I cut the connector off and carefully cut away at the grommet sealing the wire into the connector. Right in this area the inner wire sheathing had completely deteriorated. Just an inch further into the wire, everything was fine. The signal wires were shorting to the exposed ground. This is a shielded cable, with 2 sheathed wires wrapped by an exposed ground and then a foil wrapper.
For now the fix is splicing the existing speed sensor back into the harness side connector, soldering and protecting with heat shrink. I will do some serious re-wiring and buy a new sensor once it warms up a bit.
I read everything I could find on these symptoms and didn't find many specific to the ALH motor. With the G28 sensor shorting to ground the whole ECU shuts down, immediately. For anyone experiencing symptoms like this you need to investigate both the sensor wires and the main harness wires. I've got a lot of miles, but so do you guys.
By the way, with this failure and the fact that both the fueling solenoid would slam closed and the ECU wouldn't fuel the engine, you could convince yourself you had a pump failure. Cracking the injectors would show virtually no fuel!
The joys of German electrics
Jeff
Last Wednesday I went to start the car and nothing. I had some electrical issues with the grounds on the installed PD lift pump and figured my splice job had failed. After diagnosing, it was clearly not a lift pump or air situation.
The symptoms were cranking with only the occasional cough, but no real attempt to start. I investigated anything causing a bad ground to the fuel cutoff solenoid, the functionality of N109 along with all fuses. I found nothing that seemed off.
I ran VagCom and received faults for the G28, Crank Position Engine Speed Sensor and N109 implausible signal at fuel cutoff solenoid. Knowing that wire chaffing was an issue I began to investigate the wire connections along the front of the block.
After initial investigation of the connectors (black for the Cam Position, gray for the Crank/Engine speed) and some jiggling the wires I had my wife come out and crank. Car started immediately. As I was in the middle of brewing beer and the day was getting late, I left the issue for further investigation the next morning.
Next morning the car was back to no attempt to start and throwing the G28 sensor problem. So back to investigating the wiring.
I initially found severe chaffing and exposed copper on the wire loom/main harness side of the Cam Position sensor. Knowing that a problem with this sensor could also cause strange ECU codes, I cleaned the area, applied liquid electrical tape, verified there was no short. The car started right up, ran for 45 minutes through multiple start/stops etc. Pat on my back I fixed the problem.
On my commute to work the next morning I hit a bump in the road and the car died. Pulled car over, stopped, key off, car re-started immediately. I continued my trip and 10 miles later at a stop light, the car died and went back to no attempt to start.
After getting the car in a safe spot I check VagCom and initially saw the G28 code come back. I jiggled the connectors and wires a bit went back, still no start and now VagCom lost all communication for the Engine block. Not Good.
Car towed to office and I dug in further to area's that looked like corrosion might be taking place. It was clear that there was wire damage on the main harness wires coming out of the gray G28 Engine Speed sensor, but no visible damage on the side that actually goes to the sensor.
I began cutting back the sheathing going up the wire loom and found multiple cracks in the signal wires and signs of corrosion on the outer foil. Thinking I had found a short, I reconnected and tried starting, still nothing.
Now on to the sensor side wiring. Everything looked perfect. If I placed a good, Fluke, multimeter on the signal wires (positions 1 and 2) I got a nice, constant 1100ohms, in spec. Now if I jumped from 1 or 2 to the 3rd position I would see very very strange behavior. As you moved the wire about you'd see spikes from 50k ohms down to 3 ohms. Obviously a big problem.
The failure happened right where the wire goes into the gray connector. I cut the connector off and carefully cut away at the grommet sealing the wire into the connector. Right in this area the inner wire sheathing had completely deteriorated. Just an inch further into the wire, everything was fine. The signal wires were shorting to the exposed ground. This is a shielded cable, with 2 sheathed wires wrapped by an exposed ground and then a foil wrapper.
For now the fix is splicing the existing speed sensor back into the harness side connector, soldering and protecting with heat shrink. I will do some serious re-wiring and buy a new sensor once it warms up a bit.
I read everything I could find on these symptoms and didn't find many specific to the ALH motor. With the G28 sensor shorting to ground the whole ECU shuts down, immediately. For anyone experiencing symptoms like this you need to investigate both the sensor wires and the main harness wires. I've got a lot of miles, but so do you guys.
By the way, with this failure and the fact that both the fueling solenoid would slam closed and the ECU wouldn't fuel the engine, you could convince yourself you had a pump failure. Cracking the injectors would show virtually no fuel!
The joys of German electrics
Jeff
