First post here, did some searching and under charging or no charge issues are rampant.

1990 D350, auto, 5.9 Cummins

Original problem: No voltage. Replaced alternator, battery, and finally the voltage reg. Was charging at 17volts and climbing. (Blue top optima). Off the green ground wire from the voltage reg, for some reason an external relay was added on (basically a fleet vehicle, and that mechanic no longer works here nor does anyone understand why the relay is installed). Basic 85,86,87,86a, 30 black square relay. 85 is power to relay from wire spliced into voltage reg, 86 is ground, and 87 and 30 are switched to the starter.

I put the old voltage regulator in to be able to see what it was charging (or not), and now I have a no crank issue, and I realize the wiring on this is a disaster.

any ideas?

 

and the WIF and WTS lights only illuminate with the key to the crank position.

Truck also has a new tumbler and ignition switch as well.

 

moved blue wire to terminal 87a, truck fires. Charges at 14.6 volts.

The WTS light doesn't illuminate until the key is in the crank position. Going to run through basic checks at the glow plugs, but how do I determine if the brain box is or isn't functioning?

edit: pulled from alldata glow plugs don't fire until IAT is below 59F, truck has been in a heated shop for 96 hours. Just curious now about the WTS/WIF lights lighting when key in crank.

 

I'd park outside for the night to see if your WTS light comes on. If the WTS does come on check voltage at the grids to see if you are getting power. I didn't use the "brain box" when I installed the engine in my Ford, but my truck will start no problems down into the low 30's. If it gets much colder the truck will still start but takes more than a bump of the starter. I hooked my grid relays to a momentary toggle switch and run them for about 15 seconds when it gets cold before starting the truck.

I put a picture of the wiring diagram for your voltage regulator in this thread

https://www.dieseltruckresource.com/...79#post3222179

PM me if you need a brain box, you can have it for the cost of shipping.

 

Mechanic trying to compensate for a deaf or stupid driver that kept trying to start an already running engine.