Been having problems with shifting. Tried all the suggestions out there but its still doing it. Couple of different sights and posts talked about voltage spikes off of the altnator being the cause of the erratic shifting, possible bad diode.
I know if there is bad diode in the regulator it will also drain the battery over a couple of days. I had my truck sitting for 4 days and had too jump start it. I thought it was because of the terminals and cleaned them. But ever since then I've been having the erratic shifting also.
Havn't taken the altnator off yet and had it tested but with a volt meter hooked up I'm showing anywhere from 14.9 volts up to 15.4 volts charging going down the road. That seems pretty high. Checked my batteries and the battery acid is low probably because the altnator is charging to high and boiling out the acid.
Have any of you had this problem and changed out the altnator and it fixed the erratic shifting????????????

Going to pull the alnator and have it tested this weekend.

 

Getting the alternator checked is probably a good idea. I inadvertently discovered that when mine would start that business I could just move the alternator wires around and it would straighten out just from that. I figure one of these days that will quit working though.

 

If the alternator needs replaced Ill do it but if it continues with a new alternator. Then I will pull the alternator wiring from the wiring loom and reroute them seperately in their own loom with sheilding to see if that works.
Which wire is it off the alternator that everyone talks about shielding with tin foil?????

 

Anyone

 

an alternator will cause u mucho grief .make sure the voltage is correct ...i had the erratic shift 3 times already ,,,get a cold beer and clean ALL your body grounds before you go throwing money around and wrapping foil all over the place,,3 times i have cleaned mine and got a new tranny feel,CHECK yer voltage if u are over charging its no beuno

 

The alternator won't cause to high of voltage, it could cause low voltage. The alternator doesn't have a internal regulator, the alternator is regulated by the trucks computer. You may need to buy a seperate regulator to control your alternator. There are regulators avaliable but don't know what the make and model# of them are. If you do search you can likely find info about them on this forum.

 

Cleaning the 3 or 4 grounds by the batteries did it for me. I was speechless!! Fought that problem for years and did all the tricks short of replacing the alternator.

 

Pulled the alternator and had it checked and it came out ok. For curosity I also had a brand new alternator checked at the same time to compare the the voltage numbers. The numbers were identical between my used alterntor and the new alternator. Parts guy suggested trying new batteries. Didn't feel like buying new batteries until I confirmed what the problem is. Borrowed a good set of batteries from a friend and I'll see if this cures the problem. So far so good. Problem could have been the connection at the alternator not sure yet. I have cleaned almost all the grounds except the two that go to the block. I have also ran another grounding wire from the battery/body ground over to the computer grounding wire.
I did notice paint at all the body grounding points, sanded the paint off. All the body ground screws were rusty so just replaced those. Going to run another bigger grounding cable from the block to the frame and body when I clean the block grounds. I've heard of guys hooking up radio noise filters to the alternator and this also cures the shifting problems. Are they hooking in to the big wire on the back of the alternator???????

 

Before going any further with filters on the alternator, maybe unhook the alternator's field circuit to disable it, then take it for a drive to see if the problem still occurs. If it still happens, you know something else is causing it.

 

I had erratic shifting. Alternator was overcharging. So, replaced it and it didnt' solve it. Ended up having to rebuild the tranny because of the shifting and the heat that generated because of it!
At any rate, I had a "no buss" code and could not figure out *** was wrong!

After 2 shops and 3 factory Dodge PCM's we got it. Ended up being a PCM issue as that affects the alternator charging.

Do you have any codes?

 

I put one of those transmission noise filters on mine and the problem went away. $88 fix.

 

The APP noise isolator is a part number 1300030 and is available through any BD Diesel dealer. This Should take care of your issue.

 

Have not had any shifting problems since I've changed the batteries and cleaned the grounds and had the alternator checked. Alternator is charging at 14.8 under load. I still do not feel comfortable that I have found or cured the problem. I believe the problem will come back. Looking into a external regulator and noise filter. Need to find a good wiring diagram for the external regulator.

 

The voltage is on the high side and likely the reason your batteries give trouble. How is the voltage being tested on the truck? As mkrenn stated the PCM controls voltage through the field wire, not the alterator, the alternator doesn't have a internal regulator. What year is your truck? Did the shop that checked alt. check for leaking diodes or just voltage.

 

Wear of the brushes and commutator in the alternator will cause "noise" in the electrical system that isn't going to be visible on most DVM's unless you can put it on a scope. The brushes will start to stick or skip on the commutator and you will get full charge, but it will be a high frequency spike that will trip the Tranny to skip.

If you want to save some money, rebuilding it with new brushes is cheap and easy and may help to clean up the electrical output.

Larry B's Alt kits.