dim battery, brake, parkbake light help!
Moderator: martauto
I have an e30 325i when you start the cars it starts fine but the lights come on dim (battery,brake,parkbake) when I rev the car they go away but when I let it idle they come back on dim again. I have put a new battery in and a new regulator. Any suggestions on what could be wrong?
-
Brianmoooore
- E30 Zone Team Member
- Posts: 49358
- Joined: Mon Jan 10, 2005 11:00 pm
Clean off a bit of the alloy body of the alternator with sand paper, and connect a volt meter between this patch and the earthing terminal on the RH inner wing. Shouldn't be any significant voltage.
There is a fault within the instrument cluster that can turn on some of the warning lights at low revs, but it's not this if the battery warning light is amongst those coming on.
What is the voltage measured across the battery with the engine off, with the engine idling, and with it running at 3000 RPM?
Unfortunately, there's more that can go wrong with an alternator than just the regulator pack. There are also a series of diodes that convert the three phase AC electricity generated into two independent DC supplies. If one of the diodes fails it will put a large ripple into the output, confusing both ordinary volt meters and the regulator electronics.
If this is the problem, then replace it with a second hand one, fitted with your new regulator pack.
There is a fault within the instrument cluster that can turn on some of the warning lights at low revs, but it's not this if the battery warning light is amongst those coming on.
What is the voltage measured across the battery with the engine off, with the engine idling, and with it running at 3000 RPM?
Unfortunately, there's more that can go wrong with an alternator than just the regulator pack. There are also a series of diodes that convert the three phase AC electricity generated into two independent DC supplies. If one of the diodes fails it will put a large ripple into the output, confusing both ordinary volt meters and the regulator electronics.
If this is the problem, then replace it with a second hand one, fitted with your new regulator pack.
Think this should be LH inner wing.Brianmoooore wrote:Clean off a bit of the alloy body of the alternator with sand paper, and connect a volt meter between this patch and the earthing terminal on the RH inner wing.
Ben
-
Brianmoooore
- E30 Zone Team Member
- Posts: 49358
- Joined: Mon Jan 10, 2005 11:00 pm
It definitely should, and the 'L' isn't even near the 'R' on the keyboard!BenHar wrote: Think this should be LH inner wing.
-
Brianmoooore
- E30 Zone Team Member
- Posts: 49358
- Joined: Mon Jan 10, 2005 11:00 pm
The warning lights that come on other than the battery warning light are probably ones that are legally required, and are also required to have a 'test' function. These lights come on when the ignition is turned on and go off when the engine is started. The circuit that turns the 'check' off is controlled by the output on the blue wire from the alternator, and if this output drops below 12 volts while the engine is running, as a result of a fault, including a low idle speed, the 'test' can switch on again.
-
Brianmoooore
- E30 Zone Team Member
- Posts: 49358
- Joined: Mon Jan 10, 2005 11:00 pm
720 is the lowest it should be idling at, but I doubt if the tacho. is accurate to 20 RPM.
Check out the operation of the throttle position switch, to ensure the management is switching to the idle map when it should.
Check out the operation of the throttle position switch, to ensure the management is switching to the idle map when it should.