'77 M886 Alt. gauge meltdown.

Driving my '77 M886 and saw smoke coming from under the dash and noticed the alternator gauge was pegged on the charging side. At idle the gauge drops to the middle then swings wildly side to side, rev it up it and it pegs out again. I pulled the gauge cluster and the gauge was melted to the mount. I have a spare gauge cluster and swapped it out but it's trying to do the same thing, the gauge gets very hot and is erratic. What might be the problem?

Extreme over charge last time i saw that problem.

The article "Dodge M880/890" by David Ahl in Military Vehicle Magazine, May/June 2000, page 28 states "All the vehicle circuts go through the ammeter, and when (not if) it blows, everything stops dead."

This same thing happened to my M882 and after replacing the meter I used a 12 ga. jumper wire between the two gauge posts to keep it from happening again and being electrically challenged, I just went ahead and did it to see what would happen. Answer: nothing except no more fried gauges. The system will show a charge/discharge when in use and has caused no problems since . I am sure there are other opinions as to why this should not be done but the truck has worked flawlessly since. I don't think you should do what I did based solely on my ignorant electrical engineering, I post this as an example of what I did, not what you should do. Caution urged

go to this site : http://www.madelectrical.com/electricaltech/amp-gauges.shtml

you have to by pass the bulkhead connector. plus add some heavyer wires and if you want to go total crazy put the head lights on a relay.

I put my 84 Ramcharger headlights on relays and they a nice and bright now.
I did the bulkhead/ amp gauge bypass on my 69Superbee and will do the headlights over the winter.

Dodge is great but accountants hard the last word on building cars and trucks. they save $x.xx per truck new but now we spend $xxx.xx to fix them.

Joe

This happens quite a bit with these trucks. the gage goes bad and causes a short. If in a pinch, you can bolt the two wires at the Amp gage ( 10 ga. wire one red and one black ) together and bypass the gage.

Things to check will include the voltage regulator and firewall connector.

Later on tonight I will post some links from another forum where this has been discussed in length.

Actually, The link that SKAJM provided is the one you need to read....

I decided not to do the Gage conversion on my truck at this time, but I would not try to talk you out of it either... many people swear by it, They can't all be wrong.

I did however bypass the firewall connector. Here is some pictures of how I did mine just last month.

1) Cut the red wire from the engin AND the cab side of the connector and run new 10 Ga. wire threw hole ( that you have to drill ) and splice together IF the rest of the wire going to the Gage is good, If it is not good, Run the New wire straight up to the amp Gage. use a rubber gromet in the hole. They can be bought a LOWES

2) Cut the Black wire from the engin and the cab side of the of the firewall connector. Drill hole, install gromet, and splice in a new piece of 10 Ga. wire.

Note : you simply can not run this ( the Black ) wire straight to the Amp Gage because of the welded splice that is talked about in the previous mentiond link. If this portion of the wire is bad and needs replaced, you will have to also splice in the wires that feed from it....

I will post some pictures of my Firewall connector to help give you an idea of what is going on....

Note : The Battery side of my firewall connector was not bad, ( red wire ) But I did by-pass it for Prevenative Maintance

Be sure to get the charging system checked out, remember the voltage regulator ( mounted on the firewall ) has to have a good ground....

Thanks for the great info, guys. I guess I'll try a new voltage regulator to start with and bypass the firewall connector as it looks pretty ugly.

skajm said:

go to this site : http://www.madelectrical.com/electricaltech/amp-gauges.shtml

you have to by pass the bulkhead connector. plus add some heavyer wires and if you want to go total crazy put the head lights on a relay.

I put my 84 Ramcharger headlights on relays and they a nice and bright now.
I did the bulkhead/ amp gauge bypass on my 69Superbee and will do the headlights over the winter.

Dodge is great but accountants hard the last word on building cars and trucks. they save $x.xx per truck new but now we spend $xxx.xx to fix them.

Joe

Click to expand...

Thank you for the info...will do the modification on my M886 and see if it stops the overcharging and gge melt down.

skajm said:

go to this site : http://www.madelectrical.com/electricaltech/amp-gauges.shtml

you have to by pass the bulkhead connector. plus add some heavyer wires and if you want to go total crazy put the head lights on a relay.

I put my 84 Ramcharger headlights on relays and they a nice and bright now.
I did the bulkhead/ amp gauge bypass on my 69Superbee and will do the headlights over the winter.

Dodge is great but accountants hard the last word on building cars and trucks. they save $x.xx per truck new but now we spend $xxx.xx to fix them.

Joe

Click to expand...

Good catch! Great link! I found this link months ago, but wish I would have seen it before my Son's truck wiring burned up. The link should be on a sticky for the M880 Guys.

I did the above linked mod to my 880 and it fixed the problem.