My headlights, interior lights and dash lights are "pulsating" at a steady rate. very noticableat idle, seems to go away when rpm is increased.

I have a brand new voltage regulator and alternator, so how does one go about testing and diagnosing where the problem is?

One note, I replaced the regulator first, then found out that my alternator was totally bad. Is it possible that the alt damaged the regulator before I installed a new alt?

'76 Ford E-250 - 351W

 

Not likely that the alternator damaged the regulator but the regulator cut-out and kick-in voltages are far enough apart that you're noticing it in the lights, etc. Try leaving the lights on for a while (a minute or two) with the engine off (to drain the battery slightly) and see if it does it while the alternator is charging the battery at a steady rate.

 

Hm, went out and tried that, doesn't seem to make any difference. Seems to be most noticable after it's been sitting for a while, a few hours or overnight. When I fire it up the flickering is pretty obvious. I drive it for a bit and it and it's still there, but you cant really tell unless you really look for it.

Could you give me some more detail about the kick-in difference you mention? What causes (caused) it and how do you correct it?

 

Go over all your connections and grounds and make sure everything is in order.(Clean & secure attaching spots).
Especially where the voltage regulator mounts.

 

Pulsating lights tend to be ground faults in any type of vehicle. You might try unhooking one of the lights and running two jumpers right to the battery. This will tell you if it is a charging or lighting problem. Also, the radio tends to be the most sensitive appliance to charging issues. Does the light on hte radio pulse too? If it doesn't than forget the charging system. Just my opinion.

 

Bronzo, there is a small wire coming off the negative battery cable. It connects to the radiator brace, and is the primary ground circuit for the lights. Maybe the connection is loose or corroded......

 

Well, the small lead from the neg cable is in fact not connected to ground, but how does that work? I mean, if the neg cable itself is attached to the engine block, shouldn't that be supplying ground for the entire electrical system?

Spent the entire weekend going over the system, everything seems to be in place (except for the small neg lead mentioned above). Chatging system is also good, had it tested when it was in the shop last week.

Here's one thing that came to mind late last night, maybe someone could give me an opinion on it:

I have a 70amp alternator installed. The "stock" is a 40amp, but when I got the van the guy before me had installed the 70a so I replaced it with the same.

When I replaced the v-regulator, I just asked for a stock regulator for a '76 E-250. Would there be a difference between a v-regulator for a 70amp alt as opposed to a 40amp alt?

 

There wasn't a small wire on the Neg post on older trucks.

In fact, I have only seen them on GM's.


Do you have a ground strap from the back of the block to the firewall ?

You should.