Did he happen to tell you where the charging computer (voltage regulator) is located? You have the opposite problem I have. Mines putting out too much voltage and causing the GEN light to come on.

 

Did you read the thread? It is stated more than once where the regulator is located.

 

OK. so the regulator is in the pcm. I swapped mine out for another I bought from the a junk yard and get the same high reading of 16-17 then the GEN light comes on.

I did the same as OP and had the truck tested at local parts store and alternator bench tested and said good. I'm going to pull a used alternator from the junk yard and see if I get any different readings this weekend.

 

The wire coming out the the PCM, I think, is light blue with a yellow or red stripe.
I'll verify later and post back.
Am getting the part today, likely will have it installed tomorrow.

 

The wire is green/turquoise with an orange stripe.

First pic shows the wire on drivers side harness, 2nd shows it going into the computer.
Visible is my new voltage regulator, bolted to the wheel well.
Not hooked up yet, had to special order the connector for it.
I'll do a DIY when its up and running, for anyone who encounters the same problem.





edit: I have been unable to determine the proper procedure for this bybass through the ECM, so don't try tinkering around there unless you really know what you are doing. It can be done, but if you rig up the wrong wire you are very likely to fry your ECM. See below for a bypass procedure not involving the ECM.

 

I have the same problems...I would like to install an external Electronic Voltage Regulator on my Neon 1995, to avoid having to replace the entire PCM computer...

I am aware that the Alternator have 3 wires (A142, K20 and Generator Battery Terminal) and that PCM use 3 Wires (Pin 4, Pin 67 and Battery-Voltage-Sense)...

Where Do I have to Connect the External EVR...In the Generator Field Terminals A142 and K20 (and also dissable or cut the input to PCM at Pin 4 and 67).?

What about the ASD Relay (Between PCM Pin-67 and Alternator Pin-A142).?

Could you or someone give me more detailled information, wiring diagrams and parts needed to sucessfully install an external EVR in my Neon 1995?

Thanks for help!!

Bosco

 

There is a better way, I think, than going through the PCM.
You can bypass it all together and rig it up straight to the ALT.

I'll try to get more info, but as I didn't actually hook this up. this is all I have right now.

1st pic shows I installed the generic voltage regulator on a wheel well.



This pics shows how the 2 leads are spliced into the ALT.
I know this doesn't do much good without more specific info, like exactly which wires get spliced.
You can see one is green one is blue, I'll try to get some more info from the guy who hooked it up.
This worked great, charged a perfect 14V, but I ended up getting a new PCM anyhow, so its no longer hooked up.

 

Here is what the guy who hooked it up said:

Yes, splicing the blue wire and green wire from the external regulator to the blue wire and the green wire at the back of the alternator is the proper and least confusing way to do it. Ideally you should sever the green wire's connection between the ECM and the alternator to prevent the ECM's internal regulator circuit from trying to over-ride the external regulator (could cause a full field condition where the alternator over-charges the battery). The blue wire to the alternator must be kept intact, do not sever this connection... you can tap into it to connect the regulator's blue wire, but do not leave it disconnected because that is the supply wire for the alternator field. The external regulator absolutely MUST be bolted to either the vehicle body or somewhere on the engine in order for it to function.

 

Hi xray99,

Thanks for your Fast reply.?

Do you mean that I will have to connect the blue wire and green wire from the external regulator to the blue wire and the green wire at the back of the alternator.?

You also mentioned, that I should sever the green wire's connection between the ECM and the alternator (to prevent the ECM's internal regulator circuit from trying to over-ride the external regulator), Do you mean that I will have to CUT and Disconnected the Green Wire from the PCM.?

So, the External Electronic Voltage Regulator Should be connected to the blue wire and the green wire at the back of the alternator and MUST be bolted to either the vehicle body ( - Negative Voltage) or somewhere on the engine in order for it to function OK.?

What about the Check-Engine and PCM Codes.?

BTW, what brand or generic voltage regulator do you recommend me to use.?

Thanks again for help!!

 

1 - Yup.
2 - As I stated, I didn't do this hookup, and the reply above was from the guy who did, not me. Therefore I am not comfortable answering this, I'll be talking to him tomorrow and I'll see what he has to say.
* The external voltage regulator must be bolted to a good ground, probably would be hard to do it any other way if you tried.
Logical thing to do is use self tapping screws and bolt it to the wheel well, like I did.
3 - GEN light will likely keep flashing, as the computer will think there is a problem
4 - I got mine at murrays, I think I told them it was for an 89 Yukon, just to give them something to look up.
"Master Pro" regulator, part # R296