acbarnfinds

Hello guys,
Just did nv4500 swap from 727 and only hooked 1 wire up to get it started. To get it started I cut the three pin wire that goes to neutral safety and reverse light? I think, and grounded out the center pin. What's happening is my voltage is fluctuating from 13.56 to 14.56. I have never had any electrical issues w/ this truck until swap. I was wondering if it has anything to do with those wires that are not hooked up? I put a generic photo on her so you guys can see the 3 pin plug.

Well the picture wont upload so here is a link to different post.
https://www.dieseltruckresource.com/...59#post3258359

But on a side not this transmission is awesome! Goes like a bat! I went from topping out at 58mph (727) to 70 mph (nv4500) no problem, well worth the total of 32 hours into the project.

thrashingcows

If you don't put that neutral signal on a switch your Cruise won't work. The PCM neds to see the neutral ground to start, but then see that same circuit open to allow the cruise to function.

The other two are for the reverse lights. If they are grounding out, then maybe? But I doubt it.

How quick is the fluctuation in voltage? Most charging systems will move between 13.7-14.2 under regular use.

acbarnfinds

It fluctuates less then a second back and forth. Because you've don't this before I'm hoping you can help. I cut all three, grounded the middle to the frame because that's what it took to start and left the other two hanging (taped off). Well I guess I'll see what happens If I touch those two bear wires to the reverse switch at the top of the NV. How did you do yours? Oh, and my truck has no CC.

acbarnfinds

So I tied the two wires into that reverse/ neutral safety switch at the top of the nv and the reverse lights now work. Fluctuating gone but now I'm only getting 12.02 volts at the battery. Just replace VR about two months ago. Maybe the alternator went bad? I'll check fuses tomorrow and then take alt out to have tested. Sure appreciate the help.

thrashingcows

I would test your Alternator, and if it tests out fine, then I would replace the VR. These "new" off shore VR sometimes don't have much of a life span.

rrgrassi

Also test the key on voltage at the battery and the VR. That can be a problem as well. If the key on at the VR is lower than the battery voltage, the VR will begin over charging the battery.

acbarnfinds

I will give it a shot. I replaced the VR today now the truck sits at 15.1-15.2 volts and holds. Double checked all grounds and wires to VR. It has also been 21 degrees in the mornings for the last week. Would that cause it to stay at 15.1 - 15.2?

rrgrassi

Cold weather can, as it takes more amps to spin the engine and run the grid heaters at initial start. Is should settle down to 14.1 or so. If not check the key on voltage at the battery and the VR with the engine not running. IF it stays at 15.1 that is too high.

j_martin

I would check it with engine not running, and running.
If there is a significant difference, ie battery higher than at the VR, there's your problem. The regulator thinks the battery is low.

A poor ground at the VR will have exactly the same symptoms. That can be checked by putting a voltmeter between the VR mounting (frame) and battery negative. It should be extremely small.

acbarnfinds

I did all the testing I could and now dropped it off at a shop to figure out. I'll give you guys an update when I figure this out. Thanks