Well, strictly speaking it's a saab 9-3 not a vectra, but saab don't list a wiring diagram on autodata where vauxhall do.... it's a 56 plated 1.9TiD
Here's the situation, anyway. Recovered car from roadside - flat battery. Fitted fresh battery, checked charge with engine running, 11.4v so not charging. Battery light on dash not illuminated, although it lit during the self test before starting, Info display warning of low screenwash but nothing else. While driving back multiple systems failed (ABS, TC, Airbag, Power steering and gearbox control) so I limped on slowly hoping to make it back to the yard before everything failed. Couple of miles later everything came back on and the car drove fine. Soon as I got back, I put the meter on the battery again - 13.6v and rising. Gave it some load (lights on main beam, heater blower on demist) and the voltage started to drop a little but not much. Code read reveals 2 ECUs talking on CANbus, no codes stored.
Charged the original battery overnight, drop tested it this morning. it's fine. Started the car, again not charging (around 11.5v) so I went off and used autodata to find a wiring diagram.... the D+ terminal on the alternator goes to the ECM, and the "charge" light on the dash is controlled by the dashboard module, no direct connection between the two.
Unplugged the D+ wire and connected it to Battery + via a small bulb, It behaves as expected - Light goes out when engine started, Battery starts to charge (13.6 at idle rising to 13.9 when revved). Because of the unplugged wire, the charge light on the dash illuminated when I revved the car and the info display reads "Not Charging, make a safe stop". Scope on the battery shows the alt outputting rectified 3 phase with no "gaps"
SO.... my question. I'm wondering about the not charging but not warning situation, is this normal behaviour? The ECU clearly controls the alternator, and decides when it should/should not be charging, but the alt doesn't appear to be faulty and neither does the battery despite the fact that the car broke down. I'm tending towards a faulty alternator anyway, but I want to be fairly sure because it is very expensive AND a total pig to change.
Here's the situation, anyway. Recovered car from roadside - flat battery. Fitted fresh battery, checked charge with engine running, 11.4v so not charging. Battery light on dash not illuminated, although it lit during the self test before starting, Info display warning of low screenwash but nothing else. While driving back multiple systems failed (ABS, TC, Airbag, Power steering and gearbox control) so I limped on slowly hoping to make it back to the yard before everything failed. Couple of miles later everything came back on and the car drove fine. Soon as I got back, I put the meter on the battery again - 13.6v and rising. Gave it some load (lights on main beam, heater blower on demist) and the voltage started to drop a little but not much. Code read reveals 2 ECUs talking on CANbus, no codes stored.
Charged the original battery overnight, drop tested it this morning. it's fine. Started the car, again not charging (around 11.5v) so I went off and used autodata to find a wiring diagram.... the D+ terminal on the alternator goes to the ECM, and the "charge" light on the dash is controlled by the dashboard module, no direct connection between the two.
Unplugged the D+ wire and connected it to Battery + via a small bulb, It behaves as expected - Light goes out when engine started, Battery starts to charge (13.6 at idle rising to 13.9 when revved). Because of the unplugged wire, the charge light on the dash illuminated when I revved the car and the info display reads "Not Charging, make a safe stop". Scope on the battery shows the alt outputting rectified 3 phase with no "gaps"
SO.... my question. I'm wondering about the not charging but not warning situation, is this normal behaviour? The ECU clearly controls the alternator, and decides when it should/should not be charging, but the alt doesn't appear to be faulty and neither does the battery despite the fact that the car broke down. I'm tending towards a faulty alternator anyway, but I want to be fairly sure because it is very expensive AND a total pig to change.
