VR Low Voltage

[paladin06]

Well for those who followed my charging system journey know that's it's been a tough go. Well after many hours of wire fixing, new parts and more new parts, I finally got the road runner to pass the charging system electronic diagnostic test. All system pass but the test did indicate a VR low voltage.

I have done the charging system mod.

New pos and neg battey cables.

New SR and VR.

New ballast resistor

New Alt

New battery.

New ignition switch

All fusible links replaced
Any ideas?

 

[Big John]

What's the "charging system mod" and what is "SR"

What is the voltage at the battery with the engine running?

 

[paladin06]

12.36

 

[mac]

well 12.36 volts is not charging.

 

[paladin06]

SR is starter relay and the mod is a 8 gauge wire direct from the alternator to the BAT terminal on the SR and another piece from POS terminal on the battery to the BAT terminal on the SR.

 

[Jim S.]

Yes it sounds like you are just measuring battery voltage with the car running. It will probably be the same when you turn it off. I'm assuming you have dealt with the ammeter/bulkhead weak point. If so, all I can suggest is to make sure that new VR has a good ground to the firewall. Personally I do not like temporarily bypassing the VR to prove it is bad. A guy could let too much smoke out of the electrical system. :smile-new:

 

[Big John]

OK. Unlike Jim, I throw caution to the wind and I'll short the alternator field to check the system..... Seriously, I've done it and while it isn't something you want to do on a regular basis... or leave it hooked up too long, it can save you a ton of diagnostic time.

OK... Voltmeter on the battery. Disconnect the field connection. Make a small jumper wire with the spade connector on one side that will clip to the field connection on the alternator and an alligator type clip on the other end that can clip to the battery terminal on the alternator.

Put your jumper in place and start the car. Run it just as long as it takes to check the battery voltage. If it's 14 or more, your problem is with the regulator. If it's still 12, it's the alternator.

There is replacement smoke available.

 

[4spd69RR]

Lmao!

 

[Basketcase]

:basketcase:

 

[69hemibeep]

Smoke :lmao:

 

[Roadcuda]

Watch out Big's blowin' smoke again!!!!!:jester:

 

[dmartin]

where can I get a jar of that!

 

[moparmonk]

Check to make sure the Parts Guru gave you the correct alt. The 70 and up, while looking almost identical, and bolts in 100% correct, is way different. Does it have a second field wire on the brushes? 69 and back has an internal ground on the second brush that is grounded inside the alternator. As Big John said, if you supply voltage to one of the brushes, It should full field the alternator. (IE turn it on all the way) This should cause the voltage to rise to 13.8 or higher. There should be no damage as it is only Idling. (hello, these are only 37 amp output units) This eliminates the regulator from the circuit and proves the alternator good. (or bad or even incorrect) If you do have the 70 and up style, no worries. you can still check it to see if it works by grounding the second terminal and putting the 12 volts on the first terminal. It then should charge (engine running) and have 13.8 or higher. If not, replace your alternator. I have had reman alternators last less than a week. Let us know how you make out. Now, Big John, Is that bottled smoke available in Bulk?