Charging system mystery on a Datsun, Datsun was forum no help!

[WH23G3G]

I've got a charging system problem on this 76 Datsun B210 I'm working on and eventually going to sell. I just finished an engine reseal and when putting it all back together I changed the battery cables, battery, alternator, and voltage regulator. The original battery cables had the positive going to the starter, a negative cable going to a fender bolt with a soldered on bracket that had one section of the negative cable crimped and then a separate ground cable that ran to the oil pump bolt. So the negative was split by a crimped washer/retainer. Well I ordered new positive and negative battery cables from Standard ignition. They were the correct lengths, and gauge, and there was two negative cables. One to the body, and from the body to the oil pump bolt. But instead of being crimped as one cable they just had flat blade ends that you had to run the bolt through and tighten them all together to the body. The positive had a lead for the fusible length that had to be spliced in. As soon as I put the new cables on and repositioned the distributor because it was 180 off, it started right up, and immediately the CHG light and BRAKE light popped on. I checked it later with a volt meter and the alternator wasn't putting any volts out. So I took the alternator off had it tested at two parts stores and they passed both times. So since it was lifetime warranty I got another one anyway. I then assumed the voltage regulator was bad. It's an external regulator like the Chargers. Well I put that on and the new alternator, and made sure everything was hooked up and tight in the right places and it still is running strictly off the battery putting no volts out. CHG light and BRAKE light are on. I thought maybe the fusible link splice wasn't connected good enough since it ties into the voltage regulator circuit, so I switched the butt connectors to the posi-lock connectors and still nothing. It just seems highly unlikely that I would pick up a bad alternator and regulator at the same time. I know there is nothing wrong with the BRAKES, the Datsun forum said the CHG light and BRAKE light are somehow tied together but didn't know how. It's just the lights being on, the alternator is charging and voltage regulator isn't putting any volts out. Is there something obvious anyone could think off that I could've done wrong when replacing the battery cables? Could the ground on the negative cable be causing this problem? I turn here because no one on the Datsun 210 forum has a clue what to check, they're not much help and they own the same cars. I always get pointed in the right direction here or find out the problem altogether.

[71_deputy]

had one 20 years ago as a beater car. it worked flawlsy. since I have no electrical diagrams for the datsun I would check any of the wires going inside to the fuse box, ing. switch. time to see if there is voltage at the output stud of the alt- if there is then it could be in the voltage reg wiring/ grounds!!

John Mac

[mikepmcs]

I agree, check power in and out of each component with a meter(wire by wire) and recheck your grounds and power wires for continuity(end to end integrity without the car running) with a meter.  Maybe one of the new wires you put on is broken down internally.  Also is it possible a wire got chaffed and is shorting to make these lights come on and cause these problems.
I know you said you checked some stuff already but, it's possible you got burned out and frustrated and might have overlooked something(it's happened to me). I always step back, come back and do everything one by one again, even though i might have done it before.

Just some more ideas to throw out there.

good luck

v/r
Mike

[WH23G3G]

Is there a way to see if the alternator is getting power? I have the master wiring diagram from a 1976 Datsun B210 service manual, but it does me no good because I can't figure how to read it. It took me 3 times to pass the electrical chapter in high school and it was only with a C. So electrical is confusing to me. I do better looking at the actual wires than a wiring diagram. I can somewhat read the diagram but don't know how to read the routing in comparison with the actual wiring. On my alternator it has three hookups. One is a plug in harness, then there is a ground wire that is held on with a screw much like on the old tv antennas, then there is the post with the round blade connector that is bolted on. The voltage regulator is bolted to the passenger fender well covered by a bracket. Is there a place on the alternator and voltage regulator with a test light to see if it's getting power?