Hey guys, just finished doing a head gasket set replace.

When I was pulling the alternator off, the middle connector is a 10mm nut holding on a thin wire connector. Well, when I put a socket on it and tried to unscrew the nut, the entire connector post twisted in its mount and I ended up breaking the little nut/connector off of the wire, so I just set the alternator aside since I was just in the beginning of the head gasket replace procedure and wanted to make progress on that.

Well, when I got everything all buttoned up with the head gaskets, I went to grab the alternator and remembered that nut was still stuck on the connector post.

I pulled the rear plastic off the alternator (4 tiny nuts holding it on) - I had actually replaced the voltage regulator part on the back of the alternartor a couple years back and had to pull that plastic backside off when I did that so just figured I'd take a look under that cover.

After getting the back off the alternator, I was able to put a small vice grip on that post and use a socket to get the nut off of it, but the problem was that the post was spinning in its mount. I was figuring that would be a problem for something - just didn't know what. After mounting the alternator and starting the car, it appears it still charges the electrical system fine, but I noticed that my tachometer sits at zero the whole time now. So I am assuming that middle post is probably just the feed for the tach.

Has anyone had this happen to them before? Wondering if this is something I might be able to take apart and fix or if I will need to get another voltage regulator and replace it?

Thanks - Paul

 

Have another look at the wires on your alternator. For alternator AMR4247 the center lug (D) is for the dash warning light. The outer lug with the terminal connector (W) is the tachometer output. IIRC should be a white wire with a female spade connector.

 

hmmmm interesting. Thank you for the picture! I'll have another look at mine. I know I have the white wire plugged into the spade terminal.


I wonder if that twisted lug could be affecting the other terminal?

 

Could the issue with the center lug (D) be causing the problem with the ( W ) tach output, I would say possible. Those 2 terminals are very close to each other on the voltage regulator, if the center lug circuit is damaged then it's possible the tach is F'd up too. IMHO, knowing that the (D) lug is messed up, and for what a new regulator costs (and for under 1 hour to install), I'd just replace the voltage regulator.

But first, check the (W) spade terminal on the alternator is both tight and corrosion free. Also check that the female spade connector on the white wire has no corrosion. Put some dielectric grease on the terminal and see if the tach fires up. Personally, even if it works I would still replace the VR. You & I both know it's only a matter of time before the ALT Warning Lamp goes on for no reason. Good Luck!

 

Well I took the alternator back off and pulled the voltage regulator off of it.


I found a crack in the bakelite portion by the base of that middle post, so I used a jack knife to open it up a bit and saw that the connector tab had been snapped off the base of the post.



Using a multimeter I was able to check continuity and see that the post was not connected to the tab anymore. I also checked continuity between that broken tab and the other small post and there was some resistance measurement so I figured it was just that cracked connector that needed to be soldered together.


So I soldered the post to the broken connector.





then I put the rectangular cover back on with some superglue.





and then I put some hot glue over the bare lug (not shown).


Reinstalled the VR onto the back of the alternator and put it back on the disco and low-and-behold my tach is working again.


I don't doubt that broken lug was for the warning lite, but I'll bet if it is not making a connection, the tach doesn't work either.