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91.5 charging system

863 Views 4 Replies 2 Participants Last post by  mpwolf
I've got a 91.5 W250 CTD that has been a problem child since I got it 16 months ago. The charging system seems to be the biggest problem. Twice mechanics have told me that my alternator is bad, only to have it test good at the store. The first time the external voltage regulator had gone bad. I'll know this afternoon if that is the problem this time or not. Battery is known good.

I'm not sure if the rest of the issues are related, but I'm starting to think that they might be. The truck doesn't seem to be shifting into overdrive, and since getting a new flexplate a couple of weeks ago, the speedo isn't working. I also really need to stomp on the fuel to get it to roll from a dead stop.

I can't seem to find a mechanic who has any experience with these trucks, and I'm just going around in circles.
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I should say, I'm not a mechanic at all, and while I can find ideas on the net, I really don't know enough to trouble shoot very much. Once guys start throwing around the alphabet soup (ECM, CPS) I'm lost.
Just got the call from the shop- the new regulator did the trick, but now it's charging at 14V. Not sure if this is too high or not, but I'll watch it.
14v is normal charging while running.
Plowed snow for 4 hrs today and everything ran and charged great. I did notice dimming lights every time I lifted the plow. Time to seriously consider the headlight relay fix.

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