Intermitant electrical issues

[DrMackdaddy]

95 ch613 intermittent electrical problem. At random times no rhyme or reason high idle low idle loaded unloaded moving sitting still normal operating temp cold it doesn't matter, the truck just cuts off sometimes it will start back up sometimes it will not. It will start when the red engine shutdown light and the yellow electric malfunction light comes on then goes right off for the light check. It will not start when those lights do not come on, but the low brake air pressure light comes on very dim. When it does not start engine turns over fine and will continue to turn until you release the key just wont crank. I'm fairly certain that it is a ground problem. I've removed and cleaned all grounds to the block, the frame, and even the batteries. I even tried replacing the ground malfunction breaker next to the starter relay on the fire wall. Does anyone have any ideas what else i might check?

[rhasler]

Grounds should be located as follows

1. Dash Panel

a. Right hand ground can be viewed by removing the

Electrical Equipment Panel cover. The ground point will be

to the left of the Accessory Relay.

b. Left hand can be viewed by removing the ABC

gauge panel. The ground point will be in the lower left

comer, bolted to the dash stamping.

2. Ground circuit breaker, mounted on the driver's side of the

.firewall, next to the starter relay.

3. Left side engine grounds

a. Left hand engine block ground located below the starter

b. Left hand frame ground located inside the frame rail near

the starter

4. Right side engine at oil filler tube mounting bolt

Also at battery, starter, and alternator connections

[Mackpro]

95 ch613 intermittent electrical problem. At random times no rhyme or reason high idle low idle loaded unloaded moving sitting still normal operating temp cold it doesn't matter, the truck just cuts off sometimes it will start back up sometimes it will not. It will start when the red engine shutdown light and the yellow electric malfunction light comes on then goes right off for the light check. It will not start when those lights do not come on, but the low brake air pressure light comes on very dim. When it does not start engine turns over fine and will continue to turn until you release the key just wont crank. I'm fairly certain that it is a ground problem. I've removed and cleaned all grounds to the block, the frame, and even the batteries. I even tried replacing the ground malfunction breaker next to the starter relay on the fire wall. Does anyone have any ideas what else i might check?

Being this is a pre Etech engineI would replace the ingniton solinoid in the fuse box. Its the large solinoid that has the big red wires going to it. Lots of current goes through this solinoid so it gets hot (which is normal) and they seem to go bad quite often. Use a Mack solinoid and not a Napa Ford starter solinoid as thoses dont last but a week at best.

[DrMackdaddy]

Is there any way to test that solenoid?

[41chevy]

You can do a voltage drop test and check the amp draw on it, probbly cheaper to replace. seeing as it is an intermitant problem you'll have to be prepared to do it when it happens. BUT I personally would take a close look at the electrical switch connector on the key switch, since the Shut down and Malfunction lights act oddly at times. A "soft contact" or a over loaded connection could also cause it to act that way.

Paul

[DrMackdaddy]

Thank yall for all your help. Yesterday i tested that solenoid had 12.6volts on one side and1.6 on the other. i hit it with a screw driver then on both sides it had 12.6 and truck did right so i replaced the solenoid. Thanks again for all the help.