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pbanders pbanders is offline
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Join Date: Jan 2001
Location: Phoenix, AZ
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Everybody - with the help of people on the other boards, this problem has been solved. There is no design flaw with the 914 charging system, the D- ground is provided by the alternator case. The problem is that the wiring diagrams here on the PP site and in the Hayne's manual for the all but the 75-76 cars don't show that D- is connected to ground through the alternator case - but it is, as the Factory Workshop Manual shows. The problem with my car is that this ground is faulty, and by tying the VR case to ground, I'm bypassing the fault. In the stock configuration, despite what the wiring diagram for the relay board shows, there is no ground connection to the VR from the relay board.

DON'T ADD A GROUND JUMPER TO THE VR CASE! IT'S UNSAFE, SEE MY POSTING BELOW

Low charging voltage seems to be a common complaint, and it's likely that as in my case, a poor alternator ground may be the cause of the problem. The test is simple: just measure the voltage on D- with respect to chassis ground while the car is running. If you get a signficant negative voltage (mine was -1.1 V), then your alternator ground is faulty.

I didn't want to lead anyone astray by what I found - that's why I asked the community to check what I found and see if it made sense. We're lucky to have a large community of smart people who can figure out these issues quickly! It didn't make sense to me that ALL 914's would have this problem, I'm glad to see it's just a fault and not a design flaw.

Last edited by pbanders; 01-08-2007 at 07:49 PM..
Old 01-08-2007, 06:37 AM
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