Low system voltage

[Lineman20]

Hello, new to the forum                                   To get started here I bought my truck about 6 months ago (99 dodge cummins) first cummins. And everything seemed fine for a couple months then the park break and ABS lights came on, didnt think much of it as for the truck still ran perfectly fine a few weeks later I start getting this problem of idle jumping around and speedometer jumping around while driving and it jumping in and out of overdrive. (im guessing) Then just from driving around like the dumb kid I am (not being very nice to my truck) I lost my transmission, had it rebuilt by RedLine Transmissions in Boise ID. When I got it back the park break and ABS lights where still on and I still had this jumping around problem. After actually meeting Michael S. Nelson (mopar1973man) in Wieser ID. He told me it was my altinator going bad and to get it fixed before it ruins my PCM. Since then I have replaced the altinator twice. Both times I replaced it with ones you get from NAPA. Last weekend i replaced the altinator drove it all week with no issues other than the park break and ABS lights and the jumping around problem. Till this weekend after driving around Boise the check gauges lights come on and I have low voltage down to 8-10 ish volts drove it to NAPA and I fried (over heated) the altinator due to bad batteries (had the batteries checked) bought new batteries and new altinator no changes still getting check gauges light and low voltage reading on the dash gauge 

[IBMobile]

Sounds like your batteries being weak caused the diodes in the first alternator to start going bad producing high AC voltage.  This may be what caused a problem in the ABS controller.  ABS problem will need to be checked later.

 

The remanufactured alternators you buy still need to be tested for high AC voltage and with high out put demand due to weak batteries the voltage regulator in the PCM may have gone bad.

 

You're going to have to do some testing of the charging system to see what's up.  This article should help.

Then test the system for AC voltage.  See  "Update Alternator Noise testing for Dodge Cummins Trucks" in YouTube.

 

 

[GSX455]

Lineman,

I've always had the check gauges light on the dash, and voltages issue with my alternator rebuilt from NAPA.    I've heard the voltage regulators are not good on the Bosch alternators.   If you have a 99, you might have a nippendenso (ND) alternator.   If not, try to get the ND alternator, you can buy these off of Amazon.  If the voltage regulator is still acting up, Larry B's offers an external voltage regulator.   www.fostertruck.com.  Larry is very helpful.

If all else fails, you could try rebuilding your alternator with a Geno's Garage kit.

https://www.genosgarage.com/product/gould-ark-denso/engine-rebuild-kits-2

 

Have you checked for any error codes?  If you do not have a code reader, you can do the 3 ignition key turn trick.   Just turn the ignition off and on three times in a row, and the odometer display  will read error codes.   You might have a something else going bad.  I would recommend checking the ground for the alternator, should be under the passenger battery on the fender.

 

Good luck. 

[Lineman20]

Thank you IBMobile and GSX455 I'll look into these.  Hopefully come back with 

A soulutuon* 

 

[JAG1]

There are two engine block grounds also that can help reduce A/C voltage. They should be unbolted and cleaned with sand paper and retightened to the block. One is on the front driver side just above the oil pan and the other is just below the oil filter above oil pan. Follow both battery grounds down to the block and you can find them.

 

The alt. ground connector has the grey connector just below the passenger battery. Make sure all battery connectors are clean and bright will help batteries absorb some of the excess A/C voltage noise away from the PCM and ECM.

 

 

[dripley]

The key trick for codes does not work on a 99. You will need an OBDII scanner to read the codes.

[Lineman20]

Cant seem to find the alternator ground.  Not under passenger battery. Following from the altinator goes into a bundle of wires and from there idk 

[JAG1]

Its just below the passenger battery, it has a grey connector clipped to the battery tray. It's on the bottom edge facing the alternator and oil filter. A black wire about a number 8 gage wire. 

[Haggar]

Remember, on our trucks, voltage regulation is NOT in the alternator.  It is located in the PCM.     The PCM does all of the voltage regulation.  If you have some time the 8F section of the manual helps understand it a bit. 

 

HTH

Hag

2001 FSM Ram 8F-31.pdf

[Mopar1973Man]

Correct the PCM controls the voltage regulation. The blue wire is a +12 KEY wire. The GREEN wire is a variable ground lead. So these two wires need to be checked for 0 ohm from end to end to ensure that the field is being charged on the alternator. Both Bosch ND alternators are externally regulated just like it has been for around 50 years!

 

I would bench test the current alternator and verify both DC and AC ripple voltages. I doubt it will pass. Another spot to look that is commonly missed is the alternator fuse. 

[Lineman20]

Thank you for the help everyone problem solved.    Had a blown fuse and a bad relay for the shifting deal I reset the throttle positioning sensor solved that problem after changing the fuse all lights went off