Weird starting incident--tach dies
#1
Weird starting incident--tach dies
This is a bit of an academic posting since the problem went away, but since it may occur again, I think it's worth troubleshooting. Here are the details:
Starting my S5 Turbo this morning I apparently held the key in the start position, and the tach signal dropped to zero. [Car is a hard-starter due to over-rich condition at startup, so the tendency is to hold the key in the start position longer than necessary.] Car starts and is idling just fine. Check engine light comes on and I sit there completely puzzled. No rpm readings on the gauge or on the SAFC. So I sit there trying to decide how next to proceed. Check the error codes? Good idea. Check the fuses? Why not. Next thought is to try the simplest approach--shut the engine off and restart the car. Bingo! Tach is now working and car is running just fine.
I suspect there is a circuit breaker or a relay or some "smarts" in the ECU that tripped that circuit, but I can't seem to find it in the wiring diagram. Comments and ideas appreciated.
Starting my S5 Turbo this morning I apparently held the key in the start position, and the tach signal dropped to zero. [Car is a hard-starter due to over-rich condition at startup, so the tendency is to hold the key in the start position longer than necessary.] Car starts and is idling just fine. Check engine light comes on and I sit there completely puzzled. No rpm readings on the gauge or on the SAFC. So I sit there trying to decide how next to proceed. Check the error codes? Good idea. Check the fuses? Why not. Next thought is to try the simplest approach--shut the engine off and restart the car. Bingo! Tach is now working and car is running just fine.
I suspect there is a circuit breaker or a relay or some "smarts" in the ECU that tripped that circuit, but I can't seem to find it in the wiring diagram. Comments and ideas appreciated.
#3
MECP Certified Installer
This would only happen when I have just about nuked the battery and the engine would decide to fire up. This was a very rare occurrence as I usually nuked the battery first when it was that hard to start.
#5
I had this happen a couple of times before I rebuilt my engine. Engine was original with 160k on it and it was really hard to start at times when at operating temperature.
This would only happen when I have just about nuked the battery and the engine would decide to fire up. This was a very rare occurrence as I usually nuked the battery first when it was that hard to start.
This would only happen when I have just about nuked the battery and the engine would decide to fire up. This was a very rare occurrence as I usually nuked the battery first when it was that hard to start.
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