To keep with my exciting one-month old ownership of my 5th RR, I ran into the following problem. Got into the car, put the key in, turn and - nothing. I made sure I was in Park and still nothing. So far it is not at all unusual, I admit. But then I glanced at the gear indicator and, in agreement with the instruments display it was indicating 2. Physically shifting into R resulted in 3 indicated, Neutral showed D, D was still D, and from there on it was OK, 3, 2 and 1 showing correctly. Again, this was the situation:
P-2
R-3
N-D
D-D
3-3
2-2
1-1
that is, midway through the up-shifting the indication began to go backwards!
It is bad enough, but not being able to convince the BeCM that I am in either P or N meant that I could not start the engine, and I would have been stranded. I managed to start using a jumping cable directly to the smaller prong on the starter solenoid and limped to my mechanic on 3rd gear (Gearbox fault).
The obvious culprit would have been the selector position switch. We tried a couple different ones to no avail, the situation remaining as it is. We also tried another gearbox ECU, with similar results and were all ready to scrap the BeCM (what else?...).
Then, I looked at the electrical troubleshooting manual (relevant page attached). This page describes the operation of the selector switch, with its X, Y and Z selection table clearly shown. From the table it was immediately obvious that if the Z-value is alway zero, for some reason, I will get exactly the behavior we were seeing! From that point on it was just a matter of determining the cause of the constantly zero value: Either the BeCM was not able to output a high signal or the Z-line is shorted to ground. So, we took out the gearbox loom, and on the table it was immediately obvious that a burn on the outer protecting sleeve went through to the wires inside. The easy fix followed.
So, those of you who are brave enough to read to this point must wander what was the cause of the burn? well, I am not sure, but the shape and size of the burn was very much like that you would get if the burn was caused by a cigarette. This, coupled with that fact that only a day earlier my mechanic was gingerly smoking underneath the car while replacing my gearbox sump (I remember mentioning to him that this is not a good practice, and he responded by saying that diesel fuel does not readily ignite) closes the book on this case.
That is life in the Middle East for you.
P-2
R-3
N-D
D-D
3-3
2-2
1-1
that is, midway through the up-shifting the indication began to go backwards!
It is bad enough, but not being able to convince the BeCM that I am in either P or N meant that I could not start the engine, and I would have been stranded. I managed to start using a jumping cable directly to the smaller prong on the starter solenoid and limped to my mechanic on 3rd gear (Gearbox fault).
The obvious culprit would have been the selector position switch. We tried a couple different ones to no avail, the situation remaining as it is. We also tried another gearbox ECU, with similar results and were all ready to scrap the BeCM (what else?...).
Then, I looked at the electrical troubleshooting manual (relevant page attached). This page describes the operation of the selector switch, with its X, Y and Z selection table clearly shown. From the table it was immediately obvious that if the Z-value is alway zero, for some reason, I will get exactly the behavior we were seeing! From that point on it was just a matter of determining the cause of the constantly zero value: Either the BeCM was not able to output a high signal or the Z-line is shorted to ground. So, we took out the gearbox loom, and on the table it was immediately obvious that a burn on the outer protecting sleeve went through to the wires inside. The easy fix followed.
So, those of you who are brave enough to read to this point must wander what was the cause of the burn? well, I am not sure, but the shape and size of the burn was very much like that you would get if the burn was caused by a cigarette. This, coupled with that fact that only a day earlier my mechanic was gingerly smoking underneath the car while replacing my gearbox sump (I remember mentioning to him that this is not a good practice, and he responded by saying that diesel fuel does not readily ignite) closes the book on this case.
That is life in the Middle East for you.
