Battery Light

[jvest]

I’ve got a 05 6.0, but a friend is having issues with his 01 7.3 PS. About a month ago he replaced the alternator. Since then the battery light seems to go on & off intermediately. He took the alternator back to NAPA and they told him it tested good. At that point they had him replace both batteries. The next day the battery light started coming on again. Then he replaced the regulator plug, but that didn’t help. He went back to NAPA and they give him another alternator. A week went by with no problems and then all of a sudden the battery light came on and stayed on during a 100 mile trip. Since then it’s been on and off again. He brought it by my house today and left it for me to look at. The first thing I did was to verify they gave him the correct part number. It is the correct number, but is the 6G which has been an issue for rebuilders due to the difference variations in voltage regulators. Since the 6G regulator is actually located inside the alternator (not like the 4G that screws to the outside of slip ring end cover), I could not verify Rayloc installed the correct regulator. It is the gray regulator, but I believe there are at least 2 or 3 regulators that are gray, but have different color covers if you could see it.

After all that, I checked the system voltage with engine off (12.7) & engine on (14.4) and all looked good there although the light wouldn’t come on while I has checking everything. While checking out the wiring I noticed the line side (voltage in) of the glow plug relay was burnt and very hot. I removed the nut and cleaned the stud and ring terminal, then reinstalled with a new nut. I did pull the heat shrink off the ring terminal and wire to verify this connection wasn’t burnt. After doing all that, the stud still gets hot, so I assume the contact is burnt and I need to replace the relay. I don’t think this is his problem unless the contact is welding closed from time to time and draining the system down faster than the alternator can compensate. Has anyone seen this happen? I also noticed his battery cables were not very tight, but as many times as he has had them off you would think at some point they would’ve been tight and the problem go away. Does anyone suggest looking elsewhere? I connected my fluke meter inside the truck so he can at least verify voltage the next time the light comes on.


Thanks,
Jim

[SLO_F-250]

Jim,
Sorry I got no advice for you, but my early 99 7.3 PSD does the same thing. I did new batteries, tested the alternator, checked connections, and it still the light still "flickers" now and again. No codes are thrown, and I have no idea whats going on. Ill try and replace the regulator soon and see if that makes a difference.

Its pretty weird. Ill go 2 weeks without a light, then it will go on and off for two days while Im driving. Ill drive 200miles with no problem, and then on the way back it goes on for 10-20 miles and then off. No pattern.

Any input guys? Thanks!

Paul

[jvest]

Paul,

After driving about 20 miles, I was able to see the light come on. The battery voltage was running around 14 volts, so it was charging. With the engine running and the battery light on I was able to check the "I" terminal on the regulator and it was grounded which is why the light was on. I'm going to put together a bypass harness since this regulator has no computer feed back. This will help rule out something funky in the sense lead.

I worked as an engineer for a large automotive remanufacture as an engineer for 10 years, until they went out of business 4 years ago. We supplied CarQuest, Pep Boys, Auto Zone, etc... with alternators and starters. We also built some of Rayloc's low volume alternators that they didn't want to mess with. I've still got their senior engineer's (Wayne Stone) contact info if he still works there. I'll give him a call Monday and see what he thinks.

I'll keep you updated.

Jim

[03_Turbo7.3]

By chance did you try the ole voltage drop test of the positive and negative cables? maybe theres a high resistance or something in a cable you cant see?? its a 30second check that may pay off..

[SLO_F-250]

Jim,
Thanks for the reply. Please keep me updated. Next time the light comes on, Ill try to take a voltage reading. Its so random that ill just have to carry a multimeter with me. haha

What do you think about replacing the regulator? Pro/Con to this?

Paul

[jvest]

Originally Posted by 03_Turbo7.3

By chance did you try the ole voltage drop test of the positive and negative cables? maybe theres a high resistance or something in a cable you cant see?? its a 30second check that may pay off..

Yes I did check it. I had less than 4mVDC on the positive cables and less than 40mVDC on the negitive cable while running with everything on. I had an extra 6G regulator plug and indicator light that I used to make a bypass harness this afternoon since this regulator doesn't have any computer functions. When I get home tomorrow I'll take it out for a drive and see if I can get the bypass harness light to come on. I've got the light laying under the left wiper.

[jvest]

Originally Posted by SLO_F-250

Jim,
Thanks for the reply. Please keep me updated. Next time the light comes on, Ill try to take a voltage reading. Its so random that ill just have to carry a multimeter with me. haha

What do you think about replacing the regulator? Pro/Con to this?

Paul

Paul

I think these trucks come with a 4G or 6G alternator. If you have the 4G the regulator/brush assembly is easily accessible once you remove the thru bolts and pull the black cover off the back of the unit without having to pull the SRE (slip ring end) bearing. If it's a 6G the regulator/bush assembly the SRE housing and bearing will have to be removed. The plastic sleeve/retainer bushing around the SRE bearing has a lip on the inside. I suggest you replace this plastic retainer bushing because you'll tear the lip pulling the SRE housing. When you reassembly the alternator you'll need to reinstall the SRE housing and thru bolts then press the SRE bearing back in the retainer bushing. Make sure you support the pulley and drive end housing while pressing the SRE bearing because you can push the drive end (DE) bearing out of the DE housing.