Electrical power loss-help

[Mrkentee]

2010 PB 386.
Truck cut out. I got off the road. Checked wiring from batt to ecm. Replaced fuses. Swapped out ign batt feed fuse in cab. Disconnected inverter and heaters. Made it into truckstop. Code is intermittent power loss from ignition.
Will start, and run but dies.
If it sits a while, it will run a bit. That’s how I got in truckstop.
Then it will start and shut right off.
I let it idle for a while, and then it died.
Is there a thermal switch somewhere? Does that sound like a short in a wire or connector?
Help

[Nilao]

Make sure both plugs into the ecm are tight. They have an Allen head screw in the middle that loves to back out. My friend has to tighten his every year and usually gets 1 or two turns to resnug them.

[Brock]

Is it intermittent ignition power loss to ecm?

[Mrkentee]

(06-30-2018 )Nilao Wrote:  Make sure both plugs into the ecm are tight. They have an Allen head screw in the middle that loves to back out. My friend has to tighten his every year and usually gets 1 or two turns to resnug them.

Less than 1/2 turn. Still does it. Thanks

[Mrkentee]

(06-30-2018 )Brock Wrote:  Is it intermittent ignition power loss to ecm?

Yes. Now it runs for two seconds and stops, and goes back to normal.

[Brock]

http://rawze.com/forums/showthread.php?tid=2969

[Brock]

Quick run down, only a couple things it could be....... it's either a bad ground connection or the ignition power wire or a bad ecm.

On the left hand side of the ECM is a 4 pin Deusht connector with only 3 wires, one is constant power, one is switched power (your ignition power) and one is ground.

Here is your quick test..... unplug that connector and grab a couple pieces wire and 2 small bit connectors, take one of your headlight bulbs and use the ecm connector to power the headlight bulb. Slide the butt connectors onto your headlight bulb pins so you dont short the wires together.

The headlight bulb should be able to power on and be bright on either the power wire or the ignition power, if not then something is weak..... ground the headlight bulb to the frame or a known good ground, if it works then you know the ground is weak on the ecm wiring....

Hope that makes sense.

The ecm is grounded in the drivers side of the engine block directly behind the starter, there is a stud in the side of the block and a few things are grounded there, give it a turn back and forth to loosen it up and break away any built up crud. Do the same for the ground from block to starter, from starter to frame and from frame to cab firewall, also from your battery to frame.

The main power wire comes direct from the battery, on my prostar the huge wire runs from the battery to a mega fuse on my fire wall then my ecm wire runs from that to the ecm with a 30 amp fuse in line.... check that fuse!

Odds are your issue is not the actual ignition wire.

[Brock]

Here's how I tested mine... 9006 pigtails laying around though.

[Mrkentee]

(06-30-2018 )Brock Wrote:  http://rawze.com/forums/showthread.php?tid=2969

Tapped top of ecm with end of screwdriver and at first wouldn’t start. Did it again and it started. Tapped while running and it died.
Voila! Now to get one and get it programmed.