Cold start issue due to unexplained relay problem
Hi, Can anyone help with a cold start up issue. Having followed guidance in this forum, I have now got this far.
Our Seat Leon TDI continues to be difficult to start with the usual symptoms of repeated starts and eventual fire up with smoke emitted from the exhaust.
I have recently replaced all four glow plugs, having found two to be faulty. I also replaced the relay. It had a yellowish deposit coming out near the two smaller central blades.
With a new relay I have tested the voltage at the harness connections with the engine cold, and found no voltage. I checked various possibilities, and finally decided to check the new relay. I did this with a multitester as before, but this time from the inside of the car where the relay plugs into the board.
I found the relay was switching, but not producing any voltage on the output blade. I double checked there was no voltage at the harness connectors. I then decided to check the output once the engine started, and found the voltage to immediately appear on the output blade. Again I double checked the output at each harness connector, and found the voltage appear when the engine fired up, and not switch off until the engine was switched off !
It appears that the relay is switching, but in reverse. Clearly voltage at the glow plugs after the engine has started is not required, and if I ran the car with the harness connected, would probably burn the glow plugs out before too long. It also explains why I am getting poor starting because the glow plugs are not receiving any voltage before starting up.
I have tried a new relay in case there was an error with the first replacement, and exactly the same thing happens.
A bit of history which may be relevant. The ignition barrel was replaced some years ago, and I am wondering, is it possible this has been wired up incorrectly. The car has been a difficult starter over this period...non operative relay and two duff glow plugs obviously not helpful.
Any help much appreciated.