Low voltage after Alternator Upgrade?
08-12-2016, 08:10 PM
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Low voltage after Alternator Upgrade?
I upgraded my alternator to a new (not rebuilt) 180 amp Durango unit purchased from Fleabay and Torque Pro says it only is producing about 12.9 volts. I have a brand new battery that checks out OK that has been flat on occasion and I've had to get a boost.
To be fair I have not upgraded my cables and grounds yet but I'm still a little concerned. I have about 30 feet of 0 cable I'm going to make new cables with, but still shouldn't this be somewhere near 13.7-9 volts?
I was under the impression the ECM set the voltage coming from the alternator by setting the input voltage on the Stator (thus creating a stronger or weaker magnetic field).
Am I wrong? Could my ECM be going? Or is the alternator itself not producing adequate voltage?
Any one know how to test which it may be?
08-13-2016, 10:48 AM
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Just curious, why o you need a 180 Amp alternator?
Yes, the voltage should be around 13.5 volts, or above.
The PCM does have the voltage regulator in it. There is a Battery Temp Sensor in the bottom of the battery tray that provides the PCM with battery temp data, which is used by the PCM to control battery charging rate. System voltage will be higher at colder temperatures and is gradually reduced at warmer temperatures. The Battery Temp Sensor may be signaling the PCM that the battery is too hot (?).
The temp sensor connector is between the right inner fender and the battery. You may want to uncouple the connector and look for corrosion, or just shotgun a new sensor and see if it helps.
There's no need to "upgrade" your cables to AWG 0 gauge. AWG 4 cables should be adequate for any load you can put on them.
Yes, the voltage should be around 13.5 volts, or above.
The PCM does have the voltage regulator in it. There is a Battery Temp Sensor in the bottom of the battery tray that provides the PCM with battery temp data, which is used by the PCM to control battery charging rate. System voltage will be higher at colder temperatures and is gradually reduced at warmer temperatures. The Battery Temp Sensor may be signaling the PCM that the battery is too hot (?).
The temp sensor connector is between the right inner fender and the battery. You may want to uncouple the connector and look for corrosion, or just shotgun a new sensor and see if it helps.
There's no need to "upgrade" your cables to AWG 0 gauge. AWG 4 cables should be adequate for any load you can put on them.
08-13-2016, 11:14 AM
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[QUOTE=CCKen;3290898]Just curious, why o you need a 180 Amp alternator? Plan on needing it for winch and power converter etc. Plus I needed to replace original when the bearings started to seize up. So I figured what the hell, why not.
Yes, the voltage should be around 13.5 volts, or above.
That's what I thought it should be.
The PCM does have the voltage regulator in it. There is a Battery Temp Sensor in the bottom of the battery tray that provides the PCM with battery temp data, which is used by the PCM to control battery charging rate. System voltage will be higher at colder temperatures and is gradually reduced at warmer temperatures. The Battery Temp Sensor may be signaling the PCM that the battery is too hot (?).
Forgot about that sensor. Will check on it today when the monsoon we're having right now lets up.
The temp sensor connector is between the right inner fender and the battery. You may want to uncouple the connector and look for corrosion, or just shotgun a new sensor and see if it helps. Pretty sure I have one somewhere in my collection of spare parts. Is there any specs to test them for continuity or resistance first?
There's no need to "upgrade" your cables to AWG 0 gauge. AWG 4 cables should be adequate for any load you can put on them. Got the cable and lugs for free, been kicking around for years. Figured overkill on the cables can't hurt. [/QUOTE]
It's all fine wire welding cable. Lots of flex as compared to the automotive cables. Going to change out all the grounds with it too.
Yes, the voltage should be around 13.5 volts, or above.
That's what I thought it should be.
The PCM does have the voltage regulator in it. There is a Battery Temp Sensor in the bottom of the battery tray that provides the PCM with battery temp data, which is used by the PCM to control battery charging rate. System voltage will be higher at colder temperatures and is gradually reduced at warmer temperatures. The Battery Temp Sensor may be signaling the PCM that the battery is too hot (?).
Forgot about that sensor. Will check on it today when the monsoon we're having right now lets up.
The temp sensor connector is between the right inner fender and the battery. You may want to uncouple the connector and look for corrosion, or just shotgun a new sensor and see if it helps. Pretty sure I have one somewhere in my collection of spare parts. Is there any specs to test them for continuity or resistance first?
There's no need to "upgrade" your cables to AWG 0 gauge. AWG 4 cables should be adequate for any load you can put on them. Got the cable and lugs for free, been kicking around for years. Figured overkill on the cables can't hurt. [/QUOTE]
It's all fine wire welding cable. Lots of flex as compared to the automotive cables. Going to change out all the grounds with it too.
08-13-2016, 11:42 AM
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[QUOTE=Jamie57;3290905]
The temp sensor connector is between the right inner fender and the battery. You may want to uncouple the connector and look for corrosion, or just shotgun a new sensor and see if it helps.Pretty sure I have one somewhere in my collection of spare parts. Is there any specs to test them for continuity or resistance first?
I did run across testing specs a long time ago but, like a fool, neglected to save them. I'd have to try and figure it out (not now though).
[/QUOTE]
It's all fine wire welding cable. Lots of flex as compared to the automotive cables. Going to change out all the grounds with it too.
There's no need to replace the braided bonding strap from the firewall to the cylinder head bolt. It is not a primary ground.
.
.
The temp sensor connector is between the right inner fender and the battery. You may want to uncouple the connector and look for corrosion, or just shotgun a new sensor and see if it helps.Pretty sure I have one somewhere in my collection of spare parts. Is there any specs to test them for continuity or resistance first?
I did run across testing specs a long time ago but, like a fool, neglected to save them. I'd have to try and figure it out (not now though).
[/QUOTE]
It's all fine wire welding cable. Lots of flex as compared to the automotive cables. Going to change out all the grounds with it too.
There's no need to replace the braided bonding strap from the firewall to the cylinder head bolt. It is not a primary ground.
.
.
08-13-2016, 05:06 PM
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Most likely you have a bad new alternator. Fleabay....
I'll second Ken's contempt for the massive ground to the firewall. It's not needed. There is ZERO benefit to it. NONE.
It's possible it might even be a bad thing if your main ground got disconnected and that ground became your main ground. I'd rather just have the braid fry and act as a fuse. That would at least tell me something is wrong.
But it will give you 15 whp boost (at the right rear only, of course) and cure your baldness.
I'll second Ken's contempt for the massive ground to the firewall. It's not needed. There is ZERO benefit to it. NONE.
It's possible it might even be a bad thing if your main ground got disconnected and that ground became your main ground. I'd rather just have the braid fry and act as a fuse. That would at least tell me something is wrong.
But it will give you 15 whp boost (at the right rear only, of course) and cure your baldness.
08-15-2016, 08:16 PM
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Most likely you have a bad new alternator. Fleabay....
I'll second Ken's contempt for the massive ground to the firewall. It's not needed. There is ZERO benefit to it. NONE.
It's possible it might even be a bad thing if your main ground got disconnected and that ground became your main ground. I'd rather just have the braid fry and act as a fuse. That would at least tell me something is wrong.
But it will give you 15 whp boost (at the right rear only, of course) and cure your baldness.
I'll second Ken's contempt for the massive ground to the firewall. It's not needed. There is ZERO benefit to it. NONE.
It's possible it might even be a bad thing if your main ground got disconnected and that ground became your main ground. I'd rather just have the braid fry and act as a fuse. That would at least tell me something is wrong.
But it will give you 15 whp boost (at the right rear only, of course) and cure your baldness.
What a duffess I am. I had a long written report on what I had done and answers to your responses and lost it all with a wrong key press.
I can't tell of you two are joking or just jokers about that ground strap. I'm changing anyway. Found the cable today and it's 4 AWG. I still win.
Tested the battery temp sensor and it appears to be working. I checked the voltage drop from ambient to 90°C and it dropped from 2.27 to .75 VDC.
Here is the kick in the head. After removing and replacing battery terminals and renewing grounds, Torque Pro was still reporting 12.7 to 13 VDC. I had the multimeter out anyway to check the temp sensor and checked voltage at the battery terminals...... 13.77 VDC! WTF!?
So Torque Pro is reporting low voltage supposed coming from the ECM but actual voltage at the battery is correct for the charging system.
Now I'm really confused. Apparently I don't have a charging problem but I do have reporting problem.
Any ideas faithful readers? CCKen?
BTW I got my 15 WHP from changing the muffler bearings and I'm a spits throw from 60 and I still have (Almost!) all of my hair!
Just noticed another post on another thread you (BlueridgeMark) posted on where the OP got a new ECM. I had purchased a rebuilt ECM about a year before I changed out the alternator. I had someone try to steal my XJ and they broke the SKIM module antenna. Stealership was going to cost me over $1800 hard earned Canadian to "Repair". um yeah right. Got a reprogramed ECM without the SKIM for less that $300 USD.
Don't know if this would make any difference in how the ECM is reporting output voltage.
Last edited by Jamie57; 08-15-2016 at 08:31 PM. Reason: New info!
08-16-2016, 06:59 PM
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That ground strap has NO reason to be any bigger than the factory made it. There is NO possible benefit.
Ken doesn't think the battery cables need to be upgraded AT ALL. I just upgraded mine.
We both agree on the firewall ground strap. It's worse than silly to put that big thing up there.
Here is the kick in the head. After removing and replacing battery terminals and renewing grounds, Torque Pro was still reporting 12.7 to 13 VDC. I had the multimeter out anyway to check the temp sensor and checked voltage at the battery terminals...... 13.77 VDC! WTF!?
So Torque Pro is reporting low voltage supposed coming from the ECM but actual voltage at the battery is correct for the charging system.
Now I'm really confused. Apparently I don't have a charging problem but I do have reporting problem.
So Torque Pro is reporting low voltage supposed coming from the ECM but actual voltage at the battery is correct for the charging system.
Now I'm really confused. Apparently I don't have a charging problem but I do have reporting problem.
Well, great news on the muffler bearings!
Just noticed another post on another thread you (BlueridgeMark) posted on where the OP got a new ECM. I had purchased a rebuilt ECM about a year before I changed out the alternator. I had someone try to steal my XJ and they broke the SKIM module antenna. Stealership was going to cost me over $1800 hard earned Canadian to "Repair". um yeah right. Got a reprogramed ECM without the SKIM for less that $300 USD.
Don't know if this would make any difference in how the ECM is reporting output voltage.
Don't know if this would make any difference in how the ECM is reporting output voltage.
I really wouldn't worry about the reporting.
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08-18-2016, 07:53 AM
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Your voltage readings are directly from the B+ terminal?
I would test the field terminals and wiring, for voltage, continuity, gnd and ohms. IIRC I probed the field terminals for voltages and gnd where connections are made to the alternator and PCM and also performed continuity and ohms testing for the field terminal wiring.
I seem to recall some step by step troubleshooting procedures from the Jeep service manual, but can't remember all the details. The service manual usually has troubleshooting procedure both for when you have a DTC and ones for when you don't.
It was a number of years ago, the problem turned out to be the alternator with less than 20,000 miles. Wasn't working as it should with low voltage output. Came with a Delco lifetime warranty, replaced free of charge.
The PCM EVR (electronic voltage regulator) how it controls voltages to the field terminals on the alternator is it grounds the field terminals many times per second and creates a frequency (kHz) that controls voltages to the field terminals. Changes the frequency based mostly on voltage inputs (battery and alternator) and temperature sensor readings from under the battery.
Anyway this is one place to perform testing, as the alternator's fielding controls voltage output.
I would test the field terminals and wiring, for voltage, continuity, gnd and ohms. IIRC I probed the field terminals for voltages and gnd where connections are made to the alternator and PCM and also performed continuity and ohms testing for the field terminal wiring.
I seem to recall some step by step troubleshooting procedures from the Jeep service manual, but can't remember all the details. The service manual usually has troubleshooting procedure both for when you have a DTC and ones for when you don't.
It was a number of years ago, the problem turned out to be the alternator with less than 20,000 miles. Wasn't working as it should with low voltage output. Came with a Delco lifetime warranty, replaced free of charge.
The PCM EVR (electronic voltage regulator) how it controls voltages to the field terminals on the alternator is it grounds the field terminals many times per second and creates a frequency (kHz) that controls voltages to the field terminals. Changes the frequency based mostly on voltage inputs (battery and alternator) and temperature sensor readings from under the battery.
Anyway this is one place to perform testing, as the alternator's fielding controls voltage output.
Last edited by Anony; 08-18-2016 at 08:31 AM.
08-19-2016, 03:02 PM
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Your voltage readings are directly from the B+ terminal?
I would test the field terminals and wiring, for voltage, continuity, gnd and ohms. IIRC I probed the field terminals for voltages and gnd where connections are made to the alternator and PCM and also performed continuity and ohms testing for the field terminal wiring.
I seem to recall some step by step troubleshooting procedures from the Jeep service manual, but can't remember all the details. The service manual usually has troubleshooting procedure both for when you have a DTC and ones for when you don't.
It was a number of years ago, the problem turned out to be the alternator with less than 20,000 miles. Wasn't working as it should with low voltage output. Came with a Delco lifetime warranty, replaced free of charge.
The PCM EVR (electronic voltage regulator) how it controls voltages to the field terminals on the alternator is it grounds the field terminals many times per second and creates a frequency (kHz) that controls voltages to the field terminals. Changes the frequency based mostly on voltage inputs (battery and alternator) and temperature sensor readings from under the battery.
Anyway this is one place to perform testing, as the alternator's fielding controls voltage output.
I would test the field terminals and wiring, for voltage, continuity, gnd and ohms. IIRC I probed the field terminals for voltages and gnd where connections are made to the alternator and PCM and also performed continuity and ohms testing for the field terminal wiring.
I seem to recall some step by step troubleshooting procedures from the Jeep service manual, but can't remember all the details. The service manual usually has troubleshooting procedure both for when you have a DTC and ones for when you don't.
It was a number of years ago, the problem turned out to be the alternator with less than 20,000 miles. Wasn't working as it should with low voltage output. Came with a Delco lifetime warranty, replaced free of charge.
The PCM EVR (electronic voltage regulator) how it controls voltages to the field terminals on the alternator is it grounds the field terminals many times per second and creates a frequency (kHz) that controls voltages to the field terminals. Changes the frequency based mostly on voltage inputs (battery and alternator) and temperature sensor readings from under the battery.
Anyway this is one place to perform testing, as the alternator's fielding controls voltage output.
I have a more pressing problem, my heater core is leaking!!
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