Winter is almost over (I hope). Time to get ready to fix all the little things that have cropped up over the cold snowy season.

I thought I was gonna have to replace the alternator last December. The voltage regulator seemed to stop working. The voltage gauge was showing nothing higher than battery voltage for a couple of days. Then, everything seemed to start working O.K. again just before shelling out for a new alternator. Recently the v-gauge has been displaying some odd behavior again.

When I start my '96 DCTD, the voltage is at battery voltage (~12v) for the first few moments to several minutes before rising to the 14 to 15 volt range and staying there. Often the needle will bounce up and down a few times. This is when it is first started after sittilng overnight in a warm garage. When parked for shorter periods outside in winter temps the alternator will kick in and out for several minutes with the needle bouncing and headlights dimming and brightening before finally stabilizing in the 14 to 15 volt range as it should.

my assumption is that the solid state v-reg on the alternator is showing signs of being unreliable. Is this condition familiar to anyone out there? Any thoughts or suggestions on dealing with this?
Thx guys for any input on this.

 

Probably what you are seeing is the grid heaters being turned on and off.<br>They can cycle on and off for quite a while, it seems to me, but if you get<br>out on the road, they will shut off above about 12 MPH. Does this sound<br>like what you are observing?

 

Thx mechanic.<br> <br>The grid heater just might be causing the headlights to flicker. No doubt about it, it would make an ampmeter needle bounce around too. I wonder though, if it would make the needle on the voltmeter gauge vary from ~12v to ~15v. <br><br>It seems to me that the current draw shouldn't affect the volt meter gauge. But then, I could be full of it up to my eyebrows too. If the alternator had not completetly stopped putting out for several days of driving around town, I wouldn't question it. I had never noticed this happening before that. I have assumed a connection between them. <br>

 

mine does the exact same thing ...............I took it in to a garage, was told it's just the grid heaters cycling

 

The voltmeter definitely indicates when the grid heaters are on, I have<br>heard that they draw ~100Amps. I can see my headlights dim when they<br>cycle on/off after starting. You may also have another intermittent problem<br>with your alternator/regulator, though. It seems like it must have been<br>working to some extent during the time you said your voltage gauge showed<br>battery voltage for a couple of days. Grid heaters, the starter, and lights(if<br>you used them) during this period would probably have put a significant load<br>on the batteries and may have even caused them to drop to below the point<br>where they would start the truck. Sorry this doesn't seem like much help,<br>but the cycling is normal, voltmeter stuck low for a couple days isn't.<br>Hope that helps a little.

 

Thx guys. <br>Last December, I had installed a manual fuel shut-off and had shut down several times in quick succession (start-stop-start-stop...) while making an around town run when the volt meter froze at ~11 to 12v and wouldn't move above that for a few days except every once-in-a-while for a short period. <br><br>I had shut the key off first and then the fuel several of those times. I don't see how that could affect v-reg operation, but I've been meticulous about shutting fuel off first and then the electrical system ever since. <br><br>The problem went away. But, I had begun to notice the startup needle movements because of it. PARANOIA!!!<br><br>I'll watch it closely from here on out. But, I will stop worrying about it. Thx again.<br>