having issues with the charging system, I've replaced the Battery, alternator and the voltage regulator with-in the last two months. But the alternator is still not charging. what could be the issue at this point?
62savoywagon
03-28-2007, 07:25 PM
With the engine running, remove the + cable from your battery. If the engine keeps running then your alt is ok. If not it is bad. You may have short somewhere. What are the issues?
Ram4ever
03-28-2007, 11:46 PM
I had the same problem. I'd suspect a blown fusible link - look in the engine bay behind the big wire harness running along the top edge of the firewall right in front of the driver's seat. The fusible links look like heavy wires with a large rubber slug molded on their ends where they connect to wiring harness wires, and there is usually also a splice with three fusible links attached together. They may look OK, as their insulation is made of hypalon rubber, which won't melt, rather than vinyl. Best to check them with a meter.
LMin909
03-29-2007, 01:40 AM
OK. When removing the + battery cable the engine stops. I will check the fuse links tomorrow.
Dodgevanman
03-29-2007, 06:34 AM
Also check the bulkhead connector for any corrosion or melting. The "big" cable from the alt. passes through this connector to the ammeter. If there's a bad connection or if the ammeter is bad...no chargie.
B-300
03-29-2007, 03:54 PM
It's not wise to remove the battery + with the engine running.. You could damage the diodes in the alternator due to a spike in voltage.
The red wire at the alternator field should have battery voltage on it with the ignition switch in the run position. The green wire goes to the regulator which controls the field current to ground... Make sure the regulator is grounded well. The red wire at the regulator is for reference voltage and is connected to the other red wire and to the choke heater.
--B-300--
soybot
04-07-2007, 10:34 AM
i have the same story with my 78 b300. based on feedback from you guys I rewired the fusible links last weekend and it seemed to work at first (the amp meter was well into the positive for the first time i've ever seen it), but i then went down to autozone and had them test the system, both alt and battery checked "bad" (both have been replaced within the past month), and when i drove away, the gauge was back at 0. not sure if something in their test apparatus may have hurt me or what. When i rewired the fuselinks i left about 1" of the old wire where it terminates at the molded connectors. i am wondering if that little bit is now burning out. next plan is to cut that last bit out of the system, but i have to go buy a soldering iron first. any other thoughts would be appreciated.
Ram4ever
04-07-2007, 04:24 PM
:huh: Do I understand you correctly? If your battery is bad... well not much you can do to charge it, you'd have to replace it. A bad regulator could kill a new battery, but I think you'd have to run it a bit. A bad battery could also kill the voltage regulator, and if there were large spike on the power lines it could take out or damage the diodes in an alternator. I did have to go through a couple of regulators and an alternator when troubleshooting my first ever fusible link problem.
It's difficult to tell where a fusible link physically fails at. They can easily be intermittent too. I checked my Dodge service manuals and they do indicate that the rubber slugs should be completely cut away as part of the faulty link, so you might want to revisit the ones you've left in place. If the problem link is on one of the harnesses where multiple links connect together at a junction, you run the end of the replacement link completely around the junction and solder onto the wire feeding the junction.
Before doing that though, be absolutely certain that the regulator module has a good ground connection through it's mounting bolts. This is critical, and a really common problem which is quite capable of returning. I put some dielectric grease on my regulator's mounting bolts to keep moisture, oxygen and salts out.
What Nate said about the bulkhead connector is really important, any corrosion or excessive resistance anywhere in the alternator circuit will upset charging, and the bulkhead connector does corrode on our vans, and is seldom inspected.
The Dodge Service manual says that the way to narrow voltage regulation issues down to the wiring is to have the ignition key OFF, disconnect the voltage regulator cable connector, then turn the ignition key to ON and check for battery voltage on both of the cable connector's terminals. If no voltage on either one of the terminals - the problem is in the wiring.
I should also mention that the Ammeter on these vans is not very sensitive; it typically will be very close to zero even when a few accessories are in use.
In their service manuals Dodge insists that you should have a fully charged battery before performing any charging system tests. Many of the voltage regulators also come with a small slip of paper that says you should fully charge the battery before installing the new regulator, to avoid damaging it.
You may find that if curb idle is set correctly, and you measure the battery voltage you may not see much charging at idle. Even with all new components mine has to get up around 900 rpms or so to really start charging. The Dodge service manual has you set the idle at 1250 rpms for the voltage regulator test. Then they have you go straight to checking the regulator's ground if there is a problem.
