Attention: TDR Forum Junkies 
OK, if you want a more detailed story on what happened see my other thread, 'Low system voltage-help appreciated-many questions'.
I'll try to give a brief decription of the problem then elaborate on the answer.
Going to work last Wed, check gages light came on, voltage gauge low and in the red. Stopped to make sure belt had not broke, it was OK. Drove on to work another 8-10 miles. Took alternator off at my boss's shop and borrowed a company vehicle to drive home that night. Stopped at an O'Reilly's to pick up a reman alternator, they put mine on thier test bench and declared it to be OK. Confused, and not convinced that the pimply faced teenager at the counter knew what he was doing with the test machine, I dashed across town to a shop that specializes in rebuilding starters and alternators. They were locking up for the evening but agreed to test my alternator. They had an 'Old School' analog style test bench, with gauge type readouts, the tech also declared my alternator OK and handed it back to me and shoved me out the door.
Re-installed old alternator, recharged battteries and drove home 60 miles on battery power alone, alternator not charging. When I got home I verified voltage to the big red wire, and ground to the ground wire with my digital multi meter. I verified that there was 12 volts on one of the smaller lugs with the engine running, and I tried to connect the other small lug to ground, which should have engaged the alternator, but it still would not kick in and charge. I switched the ASR relay in the underhood fuse box with another one, still nothing. I ruled out that my crankshaft sensor was bad because I had none of the symptoms associated with that problem. I was not convinced that I could wire in the external voltage regulator if I could not get the alternator to charge by jumping the small lug to ground, it should have worked.
Finally after searching the internet and this website and others and coming up with virtually no good answers, I still suspected the alternator. I called a local NAPA store this morning and they said they just got a NEW computerized test bench. I again removed the alternator and took it to them. NAPA's machine immediately failed the unit, while 'Volts' and 'Amps' were in the green the test bench said "Ripple Test Failure". I asked the counter guy what that meant he said he had no idea, other than it had to do with the electronics. At my wits end and my brain fried, I gave NAPA $120, for thier 3 year warranty alternator, returned home and installed it.
PRESTO!! Problem solved!! The new alternator charges fine, I was ready to start hacking and splicing wires to install an external regulator, thinking the PCM was the culprit. I just wonder how many people have done this exact thing trying to solve a problem such as mine. An intact wiring harness is too good a thing to waste, I'm like the Dyson guy, 'I just think things should work properly'. I'm not saying wiring in the external regulator wouldn't be a cost effective solution, obviously it has worked well for many others. I was just having trouble bringing myself to actually do it.
I had never heard of the 'ripple test' before, and all of my searching online didn't turn it up, anywhere, I wasn't necessarily searching for that problem, because I had never heard of it. Just searching for 'alternator not charging' and 'low sysem voltage'
I'm just trying to do my part to help others out. Don't ask me any more questions because I'm not sure why it worked, just that it fixed my issue.
Good luck to all, as I said in my other thread, I am hoping to retire the old truck from the daily grind, hopefully by October at the latest. I'm looking at the VW Jetta and Passat right now, as they are a decently sized car at least. I went to look at a Chevy Cruze diesel and walked away without even driving it, much too small. I need it to be a family sedan as well, not just a work commuter car. Hopefully diesels will continue to gain a foothold in this country, I have been a diesel fan as long as I can remember, and continue to run our own small fleet of diesels, my 10 year old daughter likes them too, and when we test drove a new Jetta she said, 'Daddy this is too quiet for a diesel, it should be louder!' I tried to train her right, of course she wants a Beetle TDI for her 1st car! In Pink no less!
98. 5 Reg cab, 5-speed, 4x4, 3. 55's, 4" turbo back exhaust, Bosch 275 marine injectors, 375,000 miles. Van AAiken box (until it burned out, would like to have another, if someone has one)
1987 Mercedes 300D-Turbo 70k original miles, bought from a little old lady who pampered it.
1987 Mercedes 300SDL 250k original miles, it has never been pampered and is undergoing surgury for a blown head gasket.
1999 Mercedes ML430- 96k original miles, in immaculate condition and FOR SALE.
1993 Mustang 5. 0 convertible, -91k original miles, just for fun.
I'll try to give a brief decription of the problem then elaborate on the answer.
Going to work last Wed, check gages light came on, voltage gauge low and in the red. Stopped to make sure belt had not broke, it was OK. Drove on to work another 8-10 miles. Took alternator off at my boss's shop and borrowed a company vehicle to drive home that night. Stopped at an O'Reilly's to pick up a reman alternator, they put mine on thier test bench and declared it to be OK. Confused, and not convinced that the pimply faced teenager at the counter knew what he was doing with the test machine, I dashed across town to a shop that specializes in rebuilding starters and alternators. They were locking up for the evening but agreed to test my alternator. They had an 'Old School' analog style test bench, with gauge type readouts, the tech also declared my alternator OK and handed it back to me and shoved me out the door.
Re-installed old alternator, recharged battteries and drove home 60 miles on battery power alone, alternator not charging. When I got home I verified voltage to the big red wire, and ground to the ground wire with my digital multi meter. I verified that there was 12 volts on one of the smaller lugs with the engine running, and I tried to connect the other small lug to ground, which should have engaged the alternator, but it still would not kick in and charge. I switched the ASR relay in the underhood fuse box with another one, still nothing. I ruled out that my crankshaft sensor was bad because I had none of the symptoms associated with that problem. I was not convinced that I could wire in the external voltage regulator if I could not get the alternator to charge by jumping the small lug to ground, it should have worked.
Finally after searching the internet and this website and others and coming up with virtually no good answers, I still suspected the alternator. I called a local NAPA store this morning and they said they just got a NEW computerized test bench. I again removed the alternator and took it to them. NAPA's machine immediately failed the unit, while 'Volts' and 'Amps' were in the green the test bench said "Ripple Test Failure". I asked the counter guy what that meant he said he had no idea, other than it had to do with the electronics. At my wits end and my brain fried, I gave NAPA $120, for thier 3 year warranty alternator, returned home and installed it.
PRESTO!! Problem solved!! The new alternator charges fine, I was ready to start hacking and splicing wires to install an external regulator, thinking the PCM was the culprit. I just wonder how many people have done this exact thing trying to solve a problem such as mine. An intact wiring harness is too good a thing to waste, I'm like the Dyson guy, 'I just think things should work properly'. I'm not saying wiring in the external regulator wouldn't be a cost effective solution, obviously it has worked well for many others. I was just having trouble bringing myself to actually do it.
I had never heard of the 'ripple test' before, and all of my searching online didn't turn it up, anywhere, I wasn't necessarily searching for that problem, because I had never heard of it. Just searching for 'alternator not charging' and 'low sysem voltage'
I'm just trying to do my part to help others out. Don't ask me any more questions because I'm not sure why it worked, just that it fixed my issue.
Good luck to all, as I said in my other thread, I am hoping to retire the old truck from the daily grind, hopefully by October at the latest. I'm looking at the VW Jetta and Passat right now, as they are a decently sized car at least. I went to look at a Chevy Cruze diesel and walked away without even driving it, much too small. I need it to be a family sedan as well, not just a work commuter car. Hopefully diesels will continue to gain a foothold in this country, I have been a diesel fan as long as I can remember, and continue to run our own small fleet of diesels, my 10 year old daughter likes them too, and when we test drove a new Jetta she said, 'Daddy this is too quiet for a diesel, it should be louder!' I tried to train her right, of course she wants a Beetle TDI for her 1st car! In Pink no less!
98. 5 Reg cab, 5-speed, 4x4, 3. 55's, 4" turbo back exhaust, Bosch 275 marine injectors, 375,000 miles. Van AAiken box (until it burned out, would like to have another, if someone has one)
1987 Mercedes 300D-Turbo 70k original miles, bought from a little old lady who pampered it.
1987 Mercedes 300SDL 250k original miles, it has never been pampered and is undergoing surgury for a blown head gasket.
1999 Mercedes ML430- 96k original miles, in immaculate condition and FOR SALE.
1993 Mustang 5. 0 convertible, -91k original miles, just for fun.
Of course, how smart am I to argue with them??!?! :-laf
