Charging system question

Bolt

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Before you tell me to do a search. I tried and could not find a good explanation of my question. If you know the link I would be happy to read up on it. Thank you in advanced.

I was doing some preventative testing today and noticed that my charging system is not working properly. I'm outputting 12.8 volts when it should be peaking out around 14 volts. My battery is brand new and I had my alternator checked and they said it was in extremely good shape and output the 140 amps as stamped on the casing.

When my battery is slightly down and I put my charger on it the amp meter on my charger goes to 6 amps for 4 hours then it will come down to the 2 amps where it should be. OK, I max out my battery charge with my charger, I then take my car for a 30 minute drive and when I get back I should be able to put my battery charge on it and the amp meter on the charger should not go any higher than 2 amps. Guess what the amp meter goes up to 6 amps. As you know this is an indicator that my battery is not being charged my the alternator. I put my handy battery tester/voltage tester on the battery when the car is running and the indicating needle is at the bottom of the charge line. Again the battery is not charging. Now I have two indications of no or low charge.

As I was lead to believe the regulation of charge comes from the computer.

Does anyone know what my options may be?????
 
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Bolt

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The more I check this out I really think it is in the ECU.

Does anyone know the connector and pin out of the wire which goes from the alternator to the ECU? I want to check the continuity of the wire.

Anyone got a real good ECU laying around for a GENII they may want to get rid of?
 
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Bolt

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Look what I found. Pin out for the PCU. Except the alternator pin is not identified.

1996–2002 Dodge Viper ECU Diagram


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Connector A
Pin #
Name
Signal Type
8A
Crank Position Sensor Signal
Frequency
15A
Intake Temperature Sensor
Analog
18A
Camshaft Position Sensor Signal
Frequency
23A
Throttle Position Sensor
Analog
24A
Left Upstream O2 Sensor Signal
Analog
25A
Left Downstream O2 Sensor Signal
Analog
26A
Right Upstream O2 Sensor Signal
Analog
27A
MAP Sensor Signal
Analog
28A
Right Downstream O2 Sensor Signal
Analog
31A
Power Ground
Ground
32A
Power Ground
Ground​

Connector B
Pin #
Name
Signal Type
2B
Injector # 7
Frequency
3B
Injector # 9
Frequency
4B
Injector # 1
Frequency
5B
Injector # 3
Frequency
6B
Injector # 5
Frequency
12B
Injector # 6
Frequency
13B
Injector # 8
Frequency​

Connector C
Pin #
Name
Signal Type
15C
Atmospheric Temperature Sensor
Analog
31C
Tachometer Signal
RPM​
 
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GTSPOWERED

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I was having problems with my charging system. It would work great during the day but at night when the lights were on after about 1/2 hour the system would completely drop out.

I found a great alternator repair shop (Mean Green) and they repaired my alternator and have had no problems since.

Pat.
 
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Bolt

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I was having problems with my charging system. It would work great during the day but at night when the lights were on after about 1/2 hour the system would completely drop out.

I found a great alternator repair shop (Mean Green) and they repaired my alternator and have had no problems since.

Pat.

I took my alternator to a alternator shop and it tested out good. Do you think I should throw another Alternater in this? It is less cost than an ECU.
 
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Bolt

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I made a decision. I am going to put a bandage regulator on my alternator. This will throw an engine code but will help me determine if I have an alternator or ECU problem. I'll post my pics and results. This will totaly bypass the stock Viper voltage regulator system.
 

bluesrt

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just because a bench test says it good/doesnt mean its good- bench tests are shady and unreliable
 
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Bolt

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PROBLEM FIXED!

It turned out to be the alternator pulley.

The belt was hitting on the peaks of the pulley and not allowing the belt to fit down into the groves. This was pointed out to me by the technician at the alternator shop. There was glazing on the peaks and the rest of the pulley was factory black. This was not made to specs. It was out of tolerance. He tested my alternator and said it output 165 amps. He also tore it apart and he said everything was in great shape inside. He was also adamant that the ECM was not my problem and the whole problem was the pulley. Of course he did not have one in stock so I put my alternator in my bench vice and put the impact wrench on the pulley and spun it while I filed down the peaks. I took .012 in off the diameter. Tested the belt and it was hard to get it to slip. I reinstalled the alternator and it is charging great!


Yes it is a new belt on the car.
 

GTSnake

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So this is the stock pulley? How much out of tolerance was it that it was slipping? I wonder how common of a problem is this.
 
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Bolt

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So this is the stock pulley? How much out of tolerance was it that it was slipping? I wonder how common of a problem is this.

I bet this is more common than we realize. I read other post of people replacing their alternator and the problem was fixed. My pulley was the stock pulley. I also replaced the tensioner at one point. I have been chasing this problem for 4 years. Even went thru 3 batteries and 2 serpentine belts. Not that they where bad, just to find this problem. I also had this rubber smell after driving my car and parking it in my garage and could never find this smell. Over time I just gave in and lead to believe it was my tires. Even if I took it around the block I still had this rubber smell. Now I know where this was coming from. I also think the belt should rap around the alternator pulley more. Next I will be changing the pulley from the stock s-7 2 1/4 inch pulley to a s-7 2 3/8 pulley. I'll post more on this after I do this.

Another thing I noticed is lately my car wanted to stall at low RPM and did not idol well. Yes you guess it. not enough output from the alternator because the belt was slipping. Yes this could be a root cause of more engine problems being posted on this form.

I wish I had a picture of the pulley before the technician bead blasted it.
 
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Bolt

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After typing that last post I began to think about the serpentine belts I replaced. I always replaced them with the Mopar replacement ones. They look just like the gator back belts. I'll need to look into this. I just may change out my belt again with another brand. This is not an easy task when you have a paxton.
 

Tom F&L GoR

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I also had this rubber smell after driving my car and parking it in my garage and could never find this smell. Over time I just gave in and lead to believe it was my tires. Even if I took it around the block I still had this rubber smell.


I don't know, but I think you're having too much fun when you drive the car.
 
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Bolt

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I got another test I ould like to have a few of you try. Is this post goes I found a bad alternator pulley. After I filed down the points of the pulley my belt fit into the groves real good. Once the alternator was back on the can and everything was back together I did a test. I put a socket on the alternator pulley and I am now able to turn over the motor by just rotating the alternator. This tell me the belt is very tight in the groves of the pulley.

Could some of you do this test and let me know if your pulley is slipping in the belt? Also report if you are supercharged or stock. I would especialy like to hear from those of you haveing idoling problems.
 
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