temp wire gauge to cluster

oddball · Post by **oddball** » Fri Mar 15, 2013 4:09 am

good morning all

my gauge reads 260 on temp gauge on my m38a1,
the temp switch I have changed 3 x times its 24 volt electrics,

now what is going on is when I do go out on a private road the gauge goes up to 260 every now and then there is no over heating problem the gauge just goes up, I have cut the wire back and re soldered and I have now noticed there is no douglas connector there.

the gauge does not stick as when I switch engine off it goes back down.and stays down until for some reason it goes back up.

has anyone came across this problem before.

RICKG · Post by **RICKG** » Fri Mar 15, 2013 7:17 am

Go here for gage and sender testing,
http://willysmjeeps.com/v2/modules.php? ... tit&lid=46
sounds like a ground problem

scotbish · Post by **scotbish** » Sun Mar 17, 2013 5:10 am

Eddie do you want to try my Gauge mate ??

Post by **wesk** » Sun Mar 17, 2013 9:10 am

I have cut the wire back and re soldered and I have now noticed there is no douglas connector there.

Not sure of your meaning here. Post a photo of the problem wire connection.

In the mean time I have never come across a M38/M38A1 gauge problem that the Troubleshooting TB did not solve. You should have already determine weather the issue lays in gauge, sender or wire. Your issue seems to occur on bumpy private roads. That points to a motion related problem. There's no moving parts in the sender which rules it out if it passed the tests in the TB. That leaves the wiring and gauge. Intermittent problems internal to the gauge can only be resolved by substituting a known good gauge. That leaves wiring and never forget that wiring is actually circuitry and that circuitry includes wires, connectors, and metallic grounds.

Grounds can be lost due to too much fresh paint, loose fasteners, corroded fasteners, no connection. For the gauge to function correctly it must have it's housing grounded to the 24 volt power source negative side. This is done with the contact surfaces of the gauge housing, the dash instrument cluster panel the gauge retaining bracket, the cluster to dash fasteners, the engine to right front frame mount ground strap and the battery negative cable ground to the frame. The gauge internal systems rely on a path to ground through the sender.

Wiring can have bare stretches of worn off insulation that through vehicle motion occasionally come in contact with a ground. Those old Douglass connectors have rubber insulators that rot away with age and allow the pins to short to the metal cap and the metal cap can short to ground when it bumps a ground.