535i Starter spins but does not engage, electrical question

[an535i]

My car is a 1990 535i, and I have recently had my starter reconditioned after it had broken the internal fork that physically engages / disengages the starter gear.. Well i dropped the starter in and hooked up the leads went to turn the key and no start.. well I can hear the starter gear spinning but not engaging the flywheel.. so I pulled the starter and bench tested it and it seemed to work fine.. back in the car ok.. try again.. this time checked the voltage to the signal wire and it only reached about 8 volts?!?! Well I have 12.40 at the jumper terminal under the hood and 12.4+ at the battery.. Im not an electrical wiz but shouldn't the signaly be a full 12 volts?? Could this lack of voltage be causing the solenoid to not fully engage the starter gear? What circuit should I look at? Where should I start????


Thanks for ANNNY help
it is greatly appreciated.

Aaron

[632 Regal]

if it drops that much you could have a weak battery or some bad wiring. I would initially guess a bad rebuild drawing a lot of juice cause it didnt engage but maybe...just maybe you have some bad wire to the starter...I doubt it though, 1st bet be a bad rebuild. To make sure jump the thing and try, not for too long though.

[Jon K]

if it drops that much you could have a weak battery or some bad wiring. I would initially guess a bad rebuild drawing a lot of juice cause it didnt engage but maybe...just maybe you have some bad wire to the starter...I doubt it though, 1st bet be a bad rebuild. To make sure jump the thing and try, not for too long though.

Check the polarity on the starter. If you wire it backwards it will spin backwards but not engage. We put on in a car before, granted if you wire it backwards, it in theory will be always on as soon as you hook the battery up, but check still. Also, the voltage on the signal wire may only need to be like 8v or so. Are there 2 or 3 wires coming off your alternator. Another thing to keep in mind is that the starter is an extremely high-torque motor, and cold-cranking drains a TON of amperage off the battery.

[an535i]

Check the polarity on the starter. If you wire it backwards it will spin backwards but not engage. We put on in a car before, granted if you wire it backwards, it in theory will be always on as soon as you hook the battery up, but check still. Also, the voltage on the signal wire may only need to be like 8v or so. Are there 2 or 3 wires coming off your alternator. Another thing to keep in mind is that the starter is an extremely high-torque motor, and cold-cranking drains a TON of amperage off the battery.

Ya it was wired backwards.. All in all there is 4 wires on there, and I had tried to match them up by post size and the size of the wire.. WRONG... so I just tried the reverse of what I had set up and boom fired right up!

Thanks and Cheers~!
Aaron

[Jon K]

Ya it was wired backwards.. All in all there is 4 wires on there, and I had tried to match them up by post size and the size of the wire.. WRONG... so I just tried the reverse of what I had set up and boom fired right up!

Thanks and Cheers~!
Aaron

Glad I could have helped