The fix for my endless alternator failure's
07-06-2011, 10:52 AM
#323
Well, this is pissing me off. I actually have two truck alternators because last summer, the first one I bought off ebay didn't work when it showed up. Mounted it, start the car, and the voltage never moved off 11.8 volts. So I reinstalled the factory one, contacted the ebay seller, and he sent me another truck alternator, and that one worked. The seller didn't want me to send back the other one, so I stuck it in the basement.
Fast forward to this weekend. Got the procharger back up and running and the alternator isn't charging. So today, after work, I went to Pep Boys and had them check both of the truck alternators that I have and guess what, both alternators checked out fine.
So on the ride home, the only thing I thought it could be was the actual mounting of the alternator in the bracket. I was thinking that by going to the studs for the procharger, and not having that back mounting bracket, maybe I wasn't getting a good ground.
So I got home and cleaned up the mounting locations with a file, and mounted one of the alternators, crossed my fingers and started the car and nothing, voltmeter off the back of the postivie terminal on the alternator reads 11.8 volts which is the battery's voltage. So my next step was to add a grounding strap from the case of the alternator to the frame and still nothing.
So now I'm really f'in perplexed. I've got two alternators on my workbench that supposedly both check out fine, but I can't get either of them to work. What's next, the exiter wire? I checked that on Saturday and with the motor off, and the key on, it gets 11.8 volts, again, the same as the battery.
So does anyone have any suggestions?
Fast forward to this weekend. Got the procharger back up and running and the alternator isn't charging. So today, after work, I went to Pep Boys and had them check both of the truck alternators that I have and guess what, both alternators checked out fine.
So on the ride home, the only thing I thought it could be was the actual mounting of the alternator in the bracket. I was thinking that by going to the studs for the procharger, and not having that back mounting bracket, maybe I wasn't getting a good ground.
So I got home and cleaned up the mounting locations with a file, and mounted one of the alternators, crossed my fingers and started the car and nothing, voltmeter off the back of the postivie terminal on the alternator reads 11.8 volts which is the battery's voltage. So my next step was to add a grounding strap from the case of the alternator to the frame and still nothing.
So now I'm really f'in perplexed. I've got two alternators on my workbench that supposedly both check out fine, but I can't get either of them to work. What's next, the exiter wire? I checked that on Saturday and with the motor off, and the key on, it gets 11.8 volts, again, the same as the battery.
So does anyone have any suggestions?
And I just noticed that you posted above about checking it, Honestly I wouldn't even bother with checking it just get a new one at NAPA and see what happens, it may test okay when you check it with a meter but it may not make good contact when plugged in that's why I say just get a new one. Besides they are cheap and very easy to install.
07-06-2011, 11:21 AM
#324
Check for a code in the computer, I believe is a P13xx, but it will say something about terminal L. If you get that code the alternator is bad or the connector is not connected. You may have an issue with the exciter wire, I would replace the pigtail and try again.
And I just noticed that you posted above about checking it, Honestly I wouldn't even bother with checking it just get a new one at NAPA and see what happens, it may test okay when you check it with a meter but it may not make good contact when plugged in that's why I say just get a new one. Besides they are cheap and very easy to install.
And I just noticed that you posted above about checking it, Honestly I wouldn't even bother with checking it just get a new one at NAPA and see what happens, it may test okay when you check it with a meter but it may not make good contact when plugged in that's why I say just get a new one. Besides they are cheap and very easy to install.
07-06-2011, 11:55 AM
#325
I agree with you. I called my local NAPA and they will have it for me tomorrow. Who knows, maybe the prong inside the wire harness isn't making good contact with the alternator causing the issues. I stick a multi-meter in there and of course it's going to make good contact beacuse it's larger than the prong on the alternator.
07-06-2011, 01:16 PM
#326
I wonder if I could make a jumper to go to the exciter wire tonight to test it to see if it's a exciter wire issue. I really hate having problems that I don't know the resolution to. Troubleshooting problems is something I do all day long at my job, the last thing I want to do is troubleshoot more problems on something that's supposed to be my hobby/joy/relaxation.
07-06-2011, 01:45 PM
#327
I wonder if I could make a jumper to go to the exciter wire tonight to test it to see if it's a exciter wire issue. I really hate having problems that I don't know the resolution to. Troubleshooting problems is something I do all day long at my job, the last thing I want to do is troubleshoot more problems on something that's supposed to be my hobby/joy/relaxation.
Last edited by 00pooterSS; 07-06-2011 at 01:53 PM.
07-06-2011, 04:30 PM
#328
Well, it was the connector for the exciter wire. I again tested the plug and had perfect continuity back to the pcm, and was getting 10.0 volts with the ingnition on and engine off. I plugged it back in, started it up, and nothing agian. So I removed the plugs and upon closer inspection of the plug, I saw the metal tab was fully compressed, and looking at the plug on the alternator, I could see that it's only going to make contact front to back with the harness. So I grabbed a really tiny jewlers flat tip screw driver, and pried the tab forward again. Just for certainly sake, I also moved the prong on the alternator just a milimeter or so towards the contact point of the harness. Plugged it back in, started up the car, and the voltmeter went from the red to almost 15 volts in a matter of 2-3 seconds.
So I can see how all it takes is putting on the plug/harness a couple times and it's going to compress that prong, to the point that a little tension on the wire, or virbration from the engine can stop the contact and generate the l-terminal error code P1637.
So I can see how all it takes is putting on the plug/harness a couple times and it's going to compress that prong, to the point that a little tension on the wire, or virbration from the engine can stop the contact and generate the l-terminal error code P1637.
07-06-2011, 05:19 PM
#329
Well, it was the connector for the exciter wire. I again tested the plug and had perfect continuity back to the pcm, and was getting 10.0 volts with the ingnition on and engine off. I plugged it back in, started it up, and nothing agian. So I removed the plugs and upon closer inspection of the plug, I saw the metal tab was fully compressed, and looking at the plug on the alternator, I could see that it's only going to make contact front to back with the harness. So I grabbed a really tiny jewlers flat tip screw driver, and pried the tab forward again. Just for certainly sake, I also moved the prong on the alternator just a milimeter or so towards the contact point of the harness. Plugged it back in, started up the car, and the voltmeter went from the red to almost 15 volts in a matter of 2-3 seconds.
So I can see how all it takes is putting on the plug/harness a couple times and it's going to compress that prong, to the point that a little tension on the wire, or virbration from the engine can stop the contact and generate the l-terminal error code P1637.
So I can see how all it takes is putting on the plug/harness a couple times and it's going to compress that prong, to the point that a little tension on the wire, or virbration from the engine can stop the contact and generate the l-terminal error code P1637.
Hell yes! Now its time for
07-07-2011, 09:32 AM
#333
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I picked up an '03 Escalade alternator yesterday morning. Drove to my buddies shop on just the battery - died on the side of the road just past the Willow Grove Turnpike Exit at 611, about 2 mins from my buddies shop. Swapped batteries and drove to his shop. We installed the alternator yesterday afternoon. Also replaced the corroded end of the cable that runs from the alternator to the positive battery cable, just in case. It's been working great since then. We tested the voltage and it's showing right around 13.8-14.4. I need to run it under heavy acceleration as that's what was causing my 2 past failures. Need to do this ASAP before I take it to the dyno for my tuning. Thanks for the truck alternator recommendation guys!
07-07-2011, 10:47 AM
#334
I picked up an '03 Escalade alternator yesterday morning. Drove to my buddies shop on just the battery - died on the side of the road just past the Willow Grove Turnpike Exit at 611, about 2 mins from my buddies shop. Swapped batteries and drove to his shop. We installed the alternator yesterday afternoon. Also replaced the corroded end of the cable that runs from the alternator to the positive battery cable, just in case. It's been working great since then. We tested the voltage and it's showing right around 13.8-14.4. I need to run it under heavy acceleration as that's what was causing my 2 past failures. Need to do this ASAP before I take it to the dyno for my tuning. Thanks for the truck alternator recommendation guys!
But my truck alternator has seen high RPM's many times and I have had zero issues, good luck and thanks for the feedback!
07-07-2011, 11:17 AM
#335
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Did you notice corrosion on your one wire that runs from the alt. to the positive battery cable?
07-07-2011, 12:12 PM
#336
That's what I wanted to hear. My first reman failed at the track, same deal, approx 62+ miles from home. 2nd one failed about 10 miles from home on the street. I'm scared to run it now, but I have to before the dyno, so I'll be testing it (with a spare battery in my back seat just in case) shortly.
Did you notice corrosion on your one wire that runs from the alt. to the positive battery cable?
Did you notice corrosion on your one wire that runs from the alt. to the positive battery cable?
And I laughed at the spare battery statement, only because it's so sadly true lol. I have had to stop at my cousins house half way home from work and take off the alternator while it's still hot, get him to take me to the parts store (again) so I could get a replacement alternator to make it the rest of the way home. I had one alternator last 5 minutes, they are pathetic.
As far as corrosion, no I didn't have any on my car, but I generally go over board on maintaining things like that, I had free access to lifts and shop equipment nearly the entire time I have owned this car. No reason for concern though it is completely normal to have corrosion on the cables.
Unless it was at the alternator end, and if it was then I wouldn't think twice about it, I would clean it or replace it and go on down the road.
I have thought about buying a backup truck alternator since mine only cost $43.30 but ****, it seems like this one is going to last for a long time so not really a point in buying a backup, I needed a backup with the auto part store alternators
07-08-2011, 08:12 AM
#337
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That's good to hear. Hopefully I can tune it tonight. I'm going to run it a little hard during lunch to make sure it doesn't die again 
Wish me luck!
Wish me luck!
07-16-2011, 04:45 PM
#340
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Thanks OP.... I have been chasing a problem all week with my car. ever since I got the AC fixed and it got hot outside, my car has not ran right; I even posted a question in the PCM section. My tune was all over the place and I was doing nothing but chase ghost. I saw this thread last night and could not wait to try it out. I did the swap today and "bingo" all the issues went away. Big cam, 106 deg out side, and cold AC sitting still in gear. 