Voltage problem - Belt tension?
padriver
07-15-2006, 06:02 PM
I still got the problem I wrote about earlier in the following thread:
http://www.automotiveforums.com/vbulletin/showthread.php?t=560157
After replacing both the alternator and the battery, I still have the problem that the voltage is fluctuating while driving. If it does, it goes down to battery voltage level, so there seems to be no generator output at this moment. :eek7:
My guess is that there's something wrong with the belt. I wanted to check the tension, but I cannot find any tension indicator marks :confused:. The belt itself looks pretty good.
Here's a pic of the idler pulley. Maybe someone can tell from the pic if the tension is good or not. :dunno:
http://mypage.bluewin.ch/armus/pa/pics/idler_pulley.jpg
Your :2cents: are greatly appreciated.
http://www.automotiveforums.com/vbulletin/showthread.php?t=560157
After replacing both the alternator and the battery, I still have the problem that the voltage is fluctuating while driving. If it does, it goes down to battery voltage level, so there seems to be no generator output at this moment. :eek7:
My guess is that there's something wrong with the belt. I wanted to check the tension, but I cannot find any tension indicator marks :confused:. The belt itself looks pretty good.
Here's a pic of the idler pulley. Maybe someone can tell from the pic if the tension is good or not. :dunno:
http://mypage.bluewin.ch/armus/pa/pics/idler_pulley.jpg
Your :2cents: are greatly appreciated.
Cntrysthbst
07-15-2006, 09:40 PM
Your belt looks tight to me.
Did you buy an AC Delco alt.?
The negative cable on mine was bad. And needed to clean and tighten some grounds.
You can check your belt, take off the belt, flex the belt with the grooves out and see if theres any cracks, and the smooth side shouldn't look or feel like glass. Any of these indications points towards you needing a new belt. While the belts off wouldn't hurt to spin the alt pully and see if it spins freely.
I take a 12" ruler and line the belt up on the 6" mark and pull the belt both ways to measure. I haven't done this in awhile cause my belts tend to get shinny first, and when that happens I just replace them.
Did you buy an AC Delco alt.?
The negative cable on mine was bad. And needed to clean and tighten some grounds.
You can check your belt, take off the belt, flex the belt with the grooves out and see if theres any cracks, and the smooth side shouldn't look or feel like glass. Any of these indications points towards you needing a new belt. While the belts off wouldn't hurt to spin the alt pully and see if it spins freely.
I take a 12" ruler and line the belt up on the 6" mark and pull the belt both ways to measure. I haven't done this in awhile cause my belts tend to get shinny first, and when that happens I just replace them.
Cntrysthbst
07-15-2006, 09:41 PM
Maybe even a loose connection.
padriver
07-16-2006, 06:38 AM
Thanks for your input Cntrysthbst.
When I replaced the alt and battery I checked the connections and made sure they are tight.
From the symptoms, if a cable were bad, it could only be the positive one from the alt to the battery. I haven't checked it yet.
The alternator is from NQS. I doubt it's the alt because a friend of mine checked the old one and it seems to be OK.
Could something like this happen if the belt tensioner was bad?
When I replaced the alt and battery I checked the connections and made sure they are tight.
From the symptoms, if a cable were bad, it could only be the positive one from the alt to the battery. I haven't checked it yet.
The alternator is from NQS. I doubt it's the alt because a friend of mine checked the old one and it seems to be OK.
Could something like this happen if the belt tensioner was bad?
DioGreer
07-16-2006, 04:27 PM
I had a problem like this once, and I ended up replacing the positive wire leading from the battery to the alternator.
It would be at 14v while normal then suddenly I noticed voltage dropping. It never drained on me, but it would get down to about 10v and then spring back to life. Pulling over to jiggle the cable didnt help either. The voltage drop was so bad, I could tell the display for the temperature by the AC controls would be very dim. Im just lucky it didnt die on me on 85 between atlanta and greenville sc.
New wire did the trick. Got some 8 gauge wire and some big crimp connectors from a local electronics place.
It would be at 14v while normal then suddenly I noticed voltage dropping. It never drained on me, but it would get down to about 10v and then spring back to life. Pulling over to jiggle the cable didnt help either. The voltage drop was so bad, I could tell the display for the temperature by the AC controls would be very dim. Im just lucky it didnt die on me on 85 between atlanta and greenville sc.
New wire did the trick. Got some 8 gauge wire and some big crimp connectors from a local electronics place.
padriver
07-16-2006, 05:04 PM
Today, I jiggled the positive wire from the alternator to the battery while the car was idling and I did not see an effect.
Just to be sure, I'm going to check it with an ohmmeter. I guess I will change it anyway, just to be sure. It looks a little flimsy considering it has to carry all the current from the alternator.
Just to be sure, I'm going to check it with an ohmmeter. I guess I will change it anyway, just to be sure. It looks a little flimsy considering it has to carry all the current from the alternator.
Cntrysthbst
07-17-2006, 10:02 AM
Does it do this with the AC off?
The negative cable hooks up to a bolt under the coil pack, the belt gets wet sometimes when it is rainy, or snowy, or a puddle. The belt sprays the water off, now the negative that's connected under the coils is right next to the belt, and that negative cable, where it bolts, will get wet and corrode, sometimes you can't even see the corrosion cause it travels up the cable on the inside. This has happened to 2 of my PA's, and both caused voltage problems till they got replaced. Not saying this is the problem but do make sure to check that!
Does your water pump and ac pulley spin freely with the belt off? Tensioner, and alt pulley too? Your power steering pump should spin as well but not as easy. Did you check your belt for cracks on the groove side?
This is what I've done in the past, take the belt off, take it to the parts store, ask them to see the replacement belt and measure both belts together, if your belt is much longer than the new one you know it needs replaced, and if it's not, your not out any money!!! Hope this helps!
The negative cable hooks up to a bolt under the coil pack, the belt gets wet sometimes when it is rainy, or snowy, or a puddle. The belt sprays the water off, now the negative that's connected under the coils is right next to the belt, and that negative cable, where it bolts, will get wet and corrode, sometimes you can't even see the corrosion cause it travels up the cable on the inside. This has happened to 2 of my PA's, and both caused voltage problems till they got replaced. Not saying this is the problem but do make sure to check that!
Does your water pump and ac pulley spin freely with the belt off? Tensioner, and alt pulley too? Your power steering pump should spin as well but not as easy. Did you check your belt for cracks on the groove side?
This is what I've done in the past, take the belt off, take it to the parts store, ask them to see the replacement belt and measure both belts together, if your belt is much longer than the new one you know it needs replaced, and if it's not, your not out any money!!! Hope this helps!
padriver
07-17-2006, 03:21 PM
A/C on or off, doesn't make any difference.
However, I found a new suspect today: The exciter wire. Although there does not seem to be a direct correlation between the voltage drops and the illumination of the alternator lamp, I'm going to check it.
I must add that the voltage lamp has been coming on intermittently while driving, for the last couple of years. I never looked into it because the car never showed a starting or charging problem, until now.
That leaves me with four possibilities:
1. Exciter wire (or the PCM which controls this wire)
2. Wire from alternator to battery
3. Bad ground on alternator
4. Belt (or belt tension)
I'll have to go one step at a time, otherwise I'm gonna end up more confused than I already am...:screwy:
However, I found a new suspect today: The exciter wire. Although there does not seem to be a direct correlation between the voltage drops and the illumination of the alternator lamp, I'm going to check it.
I must add that the voltage lamp has been coming on intermittently while driving, for the last couple of years. I never looked into it because the car never showed a starting or charging problem, until now.
That leaves me with four possibilities:
1. Exciter wire (or the PCM which controls this wire)
2. Wire from alternator to battery
3. Bad ground on alternator
4. Belt (or belt tension)
I'll have to go one step at a time, otherwise I'm gonna end up more confused than I already am...:screwy:
padriver
07-29-2006, 06:34 PM
FYI: The problem is solved! :bananasmi
It was the PCM. The output that drives the exciter wire must be bad. With the new PCM, the voltage is as stable as can be, and I hope it stays this way (touch wood). :)
It would be great now to fix the old PCM, as this is most probably only a minor defect. Other than that, the PCM works just fine.
It was the PCM. The output that drives the exciter wire must be bad. With the new PCM, the voltage is as stable as can be, and I hope it stays this way (touch wood). :)
It would be great now to fix the old PCM, as this is most probably only a minor defect. Other than that, the PCM works just fine.
Automotive Network, Inc., Copyright ©2026