Loss of power - plenty of codes - alt not getting voltage
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Rock Crawling
Joined: Jul 2010
Posts: 435
Likes: 4
From: Lakeland, FL
Results within your reply in RED.
Am I led to believe that my alternator isn't powering at all? I will get it tested again, and then get it tested at another store too.
I will check my battery in the morning to see if it fully charged and check the cranking amps too...FYI the cranking amps were at about 75% when I tested it today.
Test 1 - voltmeter across battery terminals - looking for 12 volts or better, but will depend on if charge from alternator is reaching the battery. Less if battery is discharged.
Tested to show 12.10 (had on trickle charger for about 4 hrs to get back above 12v)
Test 2 - crank truck. Volts should come up to 13.8 - 14.4 volts at idle, no extras turned on. Will this charge up a weak battery? Maybe, but takes awhile, not just a few minutes. Better if you can charge battery with small charger overnight. If OK go to Test 3. If bad go to step 5.
Not sure about initial surge as I was doing this alone, but as soon as I got back out it was at 11.59 volts
Test 3 - with truck running, turn on things that draw lots of amps, like AC, blower on high, head light on, wiper. Volts across battery should not be below 13.2. If it is by quite a bit, alternator may have a bad diode or regulator and can't keep up with normal demand.
Turned on headlights, A/C etc and went back out and battery voltage was at 9.6 volts and steadily descending. Couldn't even get A/C to power high.
Test 4 - turn off truck and all gadgets. Read battery. While reading, switch on head lights. If volts from this moderate load drop volts to 11 or less, would suspect batttery really isn't fully charged, or perhaps has a weak or dead cell. A battery in that condition can read a good charging voltage, but when called upon for more amps the voltage drops off like a stone.
I know battery isn't fully charged, but I will charge it overnight tonight, forgot to last night.
Step 5: check wires on back of alternator for voltage, + meter lead on wire stud, (-) meter lead on alternator case. Be sure meter leads stay away from rotating parts and belt, same for pony tail or dreadlocks, fingers, etc. Big cable should read battery volts, small cable should read positive voltage. With truck running. If no positive volts on small wire, check fuse 27 under dash. If fuse OK, look at connectors and junction points shown on the RAVE electrical plan. Normally the battery trouble light will show up on instrument cluster at start up, then go out. This light is just under the tachometer on the D2. It MUST come on at startup for just a moment. If not, there is no charge function from the alternator.
Both cables on back of alt showed 11.78ish volts (same as battery at time).
Battery light does come on at start and goes away shortly after.
If both wires read good voltage on back of alternator, like the big one is 13.8 - 14.4, then read again from frame ground to the brown and red wires in the undehood fuse box - front. Also read each side of the 150 amp fuse link 1 for volts to ground, should be 13.8 - 14.4 volts. If fuse link was bad, alternator could be good, and the charging volts from it could not reach the truck or the battery. With an 11.75 volt battery reading, this would show up as 11.75 on one side of the fuselink to ground vs around 14 volts on the other side to ground.
150 amp fuse link 1 tested fine, both sides at 11.85 (same as battery at time).
If you do the above tests and believe alternator is bad, then have tested at parts store # 2 if possible. Murphy's Law applies to new store employees and test equipment as well as DIY mechanics.
In summary, 12 volts from the battery is fed thru fuses and the ignition switch to the battery warning light and on thru some connectors to the small wire on back of alternator. Big wire on alternator brings the amps back to the underhood battery boxk where it flows to the battery and all the loads of the truck.
Tested to show 12.10 (had on trickle charger for about 4 hrs to get back above 12v)
Test 2 - crank truck. Volts should come up to 13.8 - 14.4 volts at idle, no extras turned on. Will this charge up a weak battery? Maybe, but takes awhile, not just a few minutes. Better if you can charge battery with small charger overnight. If OK go to Test 3. If bad go to step 5.
Not sure about initial surge as I was doing this alone, but as soon as I got back out it was at 11.59 volts
Test 3 - with truck running, turn on things that draw lots of amps, like AC, blower on high, head light on, wiper. Volts across battery should not be below 13.2. If it is by quite a bit, alternator may have a bad diode or regulator and can't keep up with normal demand.
Turned on headlights, A/C etc and went back out and battery voltage was at 9.6 volts and steadily descending. Couldn't even get A/C to power high.
Test 4 - turn off truck and all gadgets. Read battery. While reading, switch on head lights. If volts from this moderate load drop volts to 11 or less, would suspect batttery really isn't fully charged, or perhaps has a weak or dead cell. A battery in that condition can read a good charging voltage, but when called upon for more amps the voltage drops off like a stone.
I know battery isn't fully charged, but I will charge it overnight tonight, forgot to last night.
Step 5: check wires on back of alternator for voltage, + meter lead on wire stud, (-) meter lead on alternator case. Be sure meter leads stay away from rotating parts and belt, same for pony tail or dreadlocks, fingers, etc. Big cable should read battery volts, small cable should read positive voltage. With truck running. If no positive volts on small wire, check fuse 27 under dash. If fuse OK, look at connectors and junction points shown on the RAVE electrical plan. Normally the battery trouble light will show up on instrument cluster at start up, then go out. This light is just under the tachometer on the D2. It MUST come on at startup for just a moment. If not, there is no charge function from the alternator.
Both cables on back of alt showed 11.78ish volts (same as battery at time).
Battery light does come on at start and goes away shortly after.
If both wires read good voltage on back of alternator, like the big one is 13.8 - 14.4, then read again from frame ground to the brown and red wires in the undehood fuse box - front. Also read each side of the 150 amp fuse link 1 for volts to ground, should be 13.8 - 14.4 volts. If fuse link was bad, alternator could be good, and the charging volts from it could not reach the truck or the battery. With an 11.75 volt battery reading, this would show up as 11.75 on one side of the fuselink to ground vs around 14 volts on the other side to ground.
150 amp fuse link 1 tested fine, both sides at 11.85 (same as battery at time).
If you do the above tests and believe alternator is bad, then have tested at parts store # 2 if possible. Murphy's Law applies to new store employees and test equipment as well as DIY mechanics.
In summary, 12 volts from the battery is fed thru fuses and the ignition switch to the battery warning light and on thru some connectors to the small wire on back of alternator. Big wire on alternator brings the amps back to the underhood battery boxk where it flows to the battery and all the loads of the truck.
I will check my battery in the morning to see if it fully charged and check the cranking amps too...FYI the cranking amps were at about 75% when I tested it today.
Super Moderator
Joined: Jan 2011
Posts: 16,322
Likes: 88
From: Savannah Georgia
Your tests point to needing to charge battery, and replacing alternator or having it tested by place # 2.
Now a word or two about aternators. You may have a shop in your area that rebuilds alternators and starters. They can fix this for usually under $100 or so. Their repair is better than a rebuild by a mass market company that does it for all the auto parts stores. Those firms are run by bean counterz (yes, the world needs bean counterz) who place profit ahead of reliability, and there are a high rate of failures. If you do go reman, get from some place that has life time warranty and keep copy of warranty in glove box, so when it fails and you are in LA (lower Alabama) a local store can honor it. New ones are pretty steep.
The fact that your volts stay the same from "un cranked" to "cranked and running" or actually dip a bit indicate battery is not getting charge, and it is in fact supplying all the power to the truck.
Now a word or two about aternators. You may have a shop in your area that rebuilds alternators and starters. They can fix this for usually under $100 or so. Their repair is better than a rebuild by a mass market company that does it for all the auto parts stores. Those firms are run by bean counterz (yes, the world needs bean counterz) who place profit ahead of reliability, and there are a high rate of failures. If you do go reman, get from some place that has life time warranty and keep copy of warranty in glove box, so when it fails and you are in LA (lower Alabama) a local store can honor it. New ones are pretty steep.
The fact that your volts stay the same from "un cranked" to "cranked and running" or actually dip a bit indicate battery is not getting charge, and it is in fact supplying all the power to the truck.
Thread Starter
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Rock Crawling
Joined: Jul 2010
Posts: 435
Likes: 4
From: Lakeland, FL
Your tests point to needing to charge battery, and replacing alternator or having it tested by place # 2.
Now a word or two about aternators. You may have a shop in your area that rebuilds alternators and starters. They can fix this for usually under $100 or so. Their repair is better than a rebuild by a mass market company that does it for all the auto parts stores. Those firms are run by bean counterz (yes, the world needs bean counterz) who place profit ahead of reliability, and there are a high rate of failures. If you do go reman, get from some place that has life time warranty and keep copy of warranty in glove box, so when it fails and you are in LA (lower Alabama) a local store can honor it. New ones are pretty steep.
The fact that your volts stay the same from "un cranked" to "cranked and running" or actually dip a bit indicate battery is not getting charge, and it is in fact supplying all the power to the truck.
Now a word or two about aternators. You may have a shop in your area that rebuilds alternators and starters. They can fix this for usually under $100 or so. Their repair is better than a rebuild by a mass market company that does it for all the auto parts stores. Those firms are run by bean counterz (yes, the world needs bean counterz) who place profit ahead of reliability, and there are a high rate of failures. If you do go reman, get from some place that has life time warranty and keep copy of warranty in glove box, so when it fails and you are in LA (lower Alabama) a local store can honor it. New ones are pretty steep.
The fact that your volts stay the same from "un cranked" to "cranked and running" or actually dip a bit indicate battery is not getting charge, and it is in fact supplying all the power to the truck.
I had them bench test it saturday and according to them it "tested good". Sigh. I will have them test again, and then bring it somewhere else if it passes their test again.
I do have a spare alt that should show up in the mail tomorrow, though its 100volt alt I think (for the D1), but that should work or answer my question right?
Last edited by DiscoIIBrandon; Mar 12, 2012 at 08:05 PM.
Super Moderator
Joined: Jan 2011
Posts: 16,322
Likes: 88
From: Savannah Georgia
A D1 alternator I don't think will bolt up in a D2. The D2 needs more amps than a D1 as well. You are correct that a D1 alternator is normally 100 amp rated..
This by the way is one of the great mysteries of the salvage yard, which alternators will bolt up in a Rover. Other than the tach lead, most alternators are pretty much electrically the same, but then there are all sorts of variations of mounting ears, pulley width and diameter, overall size, etc.
Why not have tested at place #2 first, for negotiation when you go to Advance, many times these testers are computerized and you get a little print out...
As for Always keep in mind: I don't know crap. I'd say you are doing pretty good.
This by the way is one of the great mysteries of the salvage yard, which alternators will bolt up in a Rover. Other than the tach lead, most alternators are pretty much electrically the same, but then there are all sorts of variations of mounting ears, pulley width and diameter, overall size, etc.
Why not have tested at place #2 first, for negotiation when you go to Advance, many times these testers are computerized and you get a little print out...
As for Always keep in mind: I don't know crap. I'd say you are doing pretty good.
Last edited by Savannah Buzz; Mar 12, 2012 at 08:52 PM.
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Rock Crawling
Joined: Jul 2010
Posts: 435
Likes: 4
From: Lakeland, FL
Updates
Well, I brought the alternator by Napa Auto parts...the guy couldn't find it in their bench tester system and therefore "couldn't test it at all"! LOL Apparently these "moron proof" advanced electrical machines only CREATE morons by enabling them to never have to think for themselves.
However, they DID recommend I go to an old local battery shop with a good ole digital bench tester that can test anything and guess what...NO amps! It took this guy all of 1 minute to hook it up and see that the alt is bad and giving no power out.
So, since I bought this alt from Advance (and don't want to buy another $300 alt) I went back to advance and of course they needed it to fail their test...
So after the guy looked around at the alt and the available harness the machine told him to use, and after he had to ask me if there were two wires connected to the alt while in the car he ran the test and it PASSED!!!!! After my skepticism of their machine and testing abilities he CONFIDENTLY told me the alt was good and that my wiring must be bad.
I've had my battery on a trickle charger overnight (was up to 12.85v an hour ago) and so after work I'm going to re-install the alternator and bring it back to Advance IN the truck and hope they can discover that either the alt or battery are bad, though I'm pretty sure the alt is bad at this point...if not, I will have to re-look over all the wiring to confirm my wiring isn't bad and possible buy a new alt from somewhere else (BP of Utah? Green machine?)
Thanks for listening to my sob story and any help/guidance.
DIIB
However, they DID recommend I go to an old local battery shop with a good ole digital bench tester that can test anything and guess what...NO amps! It took this guy all of 1 minute to hook it up and see that the alt is bad and giving no power out.
So, since I bought this alt from Advance (and don't want to buy another $300 alt) I went back to advance and of course they needed it to fail their test...
So after the guy looked around at the alt and the available harness the machine told him to use, and after he had to ask me if there were two wires connected to the alt while in the car he ran the test and it PASSED!!!!! After my skepticism of their machine and testing abilities he CONFIDENTLY told me the alt was good and that my wiring must be bad.
I've had my battery on a trickle charger overnight (was up to 12.85v an hour ago) and so after work I'm going to re-install the alternator and bring it back to Advance IN the truck and hope they can discover that either the alt or battery are bad, though I'm pretty sure the alt is bad at this point...if not, I will have to re-look over all the wiring to confirm my wiring isn't bad and possible buy a new alt from somewhere else (BP of Utah? Green machine?)
Thanks for listening to my sob story and any help/guidance.
DIIB
Thread Starter
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Rock Crawling
Joined: Jul 2010
Posts: 435
Likes: 4
From: Lakeland, FL
Alt bad
It seems we have a verdict: ALTERNATOR BAD, putting out 0 amps.
I took the truck back to Advance with the alt in and got it properly tested to show 0 amps, replacement (crappy) reman alt will be in tomorrow...hopefully this one will be better but either way I'll never get a reman junk alt, I'm afraid this won't be my last free replacement.
THanks for the help, I will post tomorrow after replacement is in and tested.
I took the truck back to Advance with the alt in and got it properly tested to show 0 amps, replacement (crappy) reman alt will be in tomorrow...hopefully this one will be better but either way I'll never get a reman junk alt, I'm afraid this won't be my last free replacement.
THanks for the help, I will post tomorrow after replacement is in and tested.
Thread Starter
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Rock Crawling
Joined: Jul 2010
Posts: 435
Likes: 4
From: Lakeland, FL
Case Closed!
Case Closed! It was a bad *reman* Alt, had worked for 1.2 years.
Got the new Alt in, started it up and whammy 14.6 volts! Put on heavy load and stayed right at 14. No more lights, no more limp mode...let's hope it stays this way for awhile.
SIDE NOTE: My Alt PASSED the bench test at Advance Auto TWICE!!!!!
Only when I had it back in the truck and it showed 0 amps did they order the replacement...luckily I didn't have to bench test it again before installing the new one, because I bet it would have passed again. Very frustrating.
Moral of the story: learn to use your multi-meter and always get a second opinion.
Got the new Alt in, started it up and whammy 14.6 volts! Put on heavy load and stayed right at 14. No more lights, no more limp mode...let's hope it stays this way for awhile.
SIDE NOTE: My Alt PASSED the bench test at Advance Auto TWICE!!!!!
Only when I had it back in the truck and it showed 0 amps did they order the replacement...luckily I didn't have to bench test it again before installing the new one, because I bet it would have passed again. Very frustrating.
Moral of the story: learn to use your multi-meter and always get a second opinion.
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