Power Wagon [886] Ambulance wiring question !!

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67Dart273 said:
IGNITION SWITCH. I would cut the "run" line coming into the engine bay and add a bosh relay. Wire the relay coil to the "run" wire on the firewall side of the wire. Hook the engine bay end of the cut wire to the switched contacts. Feed the relay power from the starter relay "big stud" through a fuse or breaker, about 20A

This will relieve load off the key switch.

Also investigate---since this is an ambulance--other added loads on the ignition switch that you maybe ought to add relays to drop those loads off the key.

It is rare but even that welded splice--under the dash--in the black ammeter wire....can and has failed
Click to expand...

Thank you for info , Im starting the troubleshooting process and will post progress as performed .
 
67Dart273 said:
Flickering / bouncing is almost never the VR unless it's the older mechanical one, but "it could be" in rare cases.

Next thing you need to do is check the bulkhead connector and check connections. Figure out the charge path from battery---through the bulkhead/ ammeter--and to the alternator. YOU MAY WELL HAVE modified wiring what was known as "fleet / taxi/ police" which ran the ammeter wiring through separate gromments in the firewall instead of the bulkhead connnector

Be ABSOLUTELY certain that the VR is well grounded to the battery You want these things well bonded together, and the larger the alternator and the more loads you have the better this must be:

Block, battery, frame, body and the VR all must be well grounded to each other. Don't be afraid to add larger cable.

CHECKING FOR VOLTAGE DROP. I've posted this a zillion times, but it is important

Check both the "harness" side and the "ground" side

1....Find ballast resistor, or as close as you can get to VR. Turn key to "run" engine stopped. Measure ballast to ground, find the highest reading which should be "battery." Stab one probe onto that and the other probe into the top of the battery POS post. You are hoping for a very low reading, the lower the better. Anything over .3V look for why.

I cannot tell you on that "rig" on a "stocker" the "general" path is battery..........starter relay big stud...........fuse link..........through the bulkhead (RED ammeter wire)............to and through the ammeter.........out on BLACK..........to the WELDED SPLICE under the dash...........branch off to igntiion switch connector............through switch........back out on "igntiion run" IGN1..........back out bulkhead usually dark blue...........to ballast.........branch off to VR and other underhood loads, alternator field...........smog equipment...........electric choke.........THAT VEHICLE MAY HAVE a "field loads" relay

2.....Check ground. Get engine warm, battery "normalized" and running on fast idle to simulate "low to medium cruise" RPM. Run this test first with all loads off, again with lights, heater, etc powered on

Stab one probe of your meter into top of battery NEG post. Stab remaining probe into mounting flange of VR. Be sure to stab through paint, rust. Once again, you are hoping for a very low reading, zero volts would be perfect

If you do all this and it won't settle down, run the thing at various RPM and various light and heavy loads while montoring the alternator output stud to the battery POS post. If your meter reads an absolute maximum of 2V under heavy load you are on the borderline. If that voltage jumps around while the load is "stable" you may have a bad connection in the charge line to battery. Also "rig" a heavy wire like no14 with a female "flag" push on connector to fit where the BLUE field wire is connected. Jumper that wire over to the battery GOOD connection. See if that settles it down. Note of course this is a test and not to be driven that way, as the alternator field will be powered / key off

Also re-check alternator for problems especially brushes and a bad stator, and replace VR
Click to expand...
Update !
Ran ground wire 10g from battery to one nut holding VR on and off the other nut on VR made a 8 g wire from it to valve cover stud/ replaced bolt !!
Still bouncing also checked both of those grounds hooked test light to battery stud on alt with engine running and tested against both new attachment points and body of VR and all grounds are good even checked other spots on motor all good !!!
Test light was slightly flickering while performing this volts 15.20 to 15.60 @ idle
 
I would double check condition of brushes and try a new VR.
 
67Dart273 said:
I would double check condition of brushes and try a new VR.
Click to expand...
I bought 100 amp alternator from a member said it was like new , I just installed it , the one that was taken off yesterday when idling the headlights would flicker the new one installed isnt doing that lights are stable @ idle.
VR is new - I will take alternator I pulled off yesterday and go have it tested this week just to be sure.
 
i have an M880 and the ammeter was doing the same, the lights also flickered but i didn't worry about that as every old mopar i've had has done that. I also noticed the light to illuminate my auto meter fuel gauge would flicker just like the other stuff. My alternator died so I put another on and I still had the flicker in the lights. I think I also replaced the voltage regulator. Didn't help.
I figured out that my bulkhead connection was pretty bad so i bypassed that, put a voltage gauge on and converted to the Denso style alternator. The light in the fuel gauge doesn't flicker now...i actually left the ammeter in the truck but it's doesn't do anything now the way the alt output is wired up.
 
cookietruck said:
i have an M880 and the ammeter was doing the same, the lights also flickered but i didn't worry about that as every old mopar i've had has done that. I also noticed the light to illuminate my auto meter fuel gauge would flicker just like the other stuff. My alternator died so I put another on and I still had the flicker in the lights. I think I also replaced the voltage regulator. Didn't help.
I figured out that my bulkhead connection was pretty bad so i bypassed that, put a voltage gauge on and converted to the Denso style alternator. The light in the fuel gauge doesn't flicker now...i actually left the ammeter in the truck but it's doesn't do anything now the way the alt output is wired up.
Click to expand...
Exact issues im having I guess it was common problem mine charges good its the flickering all the time thats weird
 
67Dart273 said:
Flickering / bouncing is almost never the VR unless it's the older mechanical one, but "it could be" in rare cases.

Next thing you need to do is check the bulkhead connector and check connections. Figure out the charge path from battery---through the bulkhead/ ammeter--and to the alternator. YOU MAY WELL HAVE modified wiring what was known as "fleet / taxi/ police" which ran the ammeter wiring through separate gromments in the firewall instead of the bulkhead connnector

Be ABSOLUTELY certain that the VR is well grounded to the battery You want these things well bonded together, and the larger the alternator and the more loads you have the better this must be:

Block, battery, frame, body and the VR all must be well grounded to each other. Don't be afraid to add larger cable.

CHECKING FOR VOLTAGE DROP. I've posted this a zillion times, but it is important

Check both the "harness" side and the "ground" side

1....Find ballast resistor, or as close as you can get to VR. Turn key to "run" engine stopped. Measure ballast to ground, find the highest reading which should be "battery." Stab one probe onto that and the other probe into the top of the battery POS post. You are hoping for a very low reading, the lower the better. Anything over .3V look for why.

I cannot tell you on that "rig" on a "stocker" the "general" path is battery..........starter relay big stud...........fuse link..........through the bulkhead (RED ammeter wire)............to and through the ammeter.........out on BLACK..........to the WELDED SPLICE under the dash...........branch off to igntiion switch connector............through switch........back out on "igntiion run" IGN1..........back out bulkhead usually dark blue...........to ballast.........branch off to VR and other underhood loads, alternator field...........smog equipment...........electric choke.........THAT VEHICLE MAY HAVE a "field loads" relay

2.....Check ground. Get engine warm, battery "normalized" and running on fast idle to simulate "low to medium cruise" RPM. Run this test first with all loads off, again with lights, heater, etc powered on

Stab one probe of your meter into top of battery NEG post. Stab remaining probe into mounting flange of VR. Be sure to stab through paint, rust. Once again, you are hoping for a very low reading, zero volts would be perfect

If you do all this and it won't settle down, run the thing at various RPM and various light and heavy loads while montoring the alternator output stud to the battery POS post. If your meter reads an absolute maximum of 2V under heavy load you are on the borderline. If that voltage jumps around while the load is "stable" you may have a bad connection in the charge line to battery. Also "rig" a heavy wire like no14 with a female "flag" push on connector to fit where the BLUE field wire is connected. Jumper that wire over to the battery GOOD connection. See if that settles it down. Note of course this is a test and not to be driven that way, as the alternator field will be powered / key off

Also re-check alternator for problems especially brushes and a bad stator, and replace VR
Click to expand...

Ok going to check this all this weekend I put another alt on and same problem so must be what u mentioned
 
Good luck. With the special wiring in such a vehicle, no idea "what else". I would concentrate on the field circuit "voltage drop" or the charge path to the battery same deal. Bad terminals, poor connections, etc
 
67Dart273 said:
Good luck. With the special wiring in such a vehicle, no idea "what else". I would concentrate on the field circuit "voltage drop" or the charge path to the battery same deal. Bad terminals, poor connections, etc
Click to expand...

Yes sir - its just aggravating more than anything truck is reliable
 
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