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F650 with Caterpillar C7 ACERT

S

steevz

Active Member
Joined
Jul 16, 2012
Messages
31
Location
Vancouver, BC
The truck was running fine. It was driven for a delivery first thing in the morning, left it idle back at the shop. About 15 minutes later, it was moved and turned off.

Later in the afternoon, the truck wouldn't start. At first I thought it was the intake heater, because the "Wait to Start" light was not coming on, and it say for approximately 6 hours. This is bizarre, because the truck did not die. It was physically turned off, and will not restart.


In-line fuse at the battery has voltage for the ECM. When cranking there is no smoke, the plug going into the HPOP is not getting voltage while cranking. The intake heater relay is not getting ground when turned on. Not getting a Check Engine light OR Wait to Start light when the key is first turned for a couple seconds.

All signs look like they're pointing to the ECM not getting power. I don't know if there are any more hidden fuses to power the ECM. Both the plugs going into it are tight. I'm running out of ideas and would love it if someone could chime in. Ignition? Fuses? Relay?
 
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Birken Vogt

Charter Member
Joined
Nov 30, 2003
Messages
5,323
Location
Grass Valley, Ca
We had one with gremlins like this and the WTS light was our clue whether to start chasing battery issues (again) or to look at something mechanical. There were so many things that regularly went wrong with that engine it was mind boggling and we had a system down to quickly trouble shoot which one it was.

Suffice it to say that you need to check your ECM battery power again and thoroughly. If I recall there might have been more than one wire and more than one fuse?
 
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Dad5

Well-Known Member
Joined
Jan 15, 2011
Messages
79
Location
Nova Scotia
In the rear most 70 pin plug on the engine ECM the following pin are power and grounds.
Pin 70 - Ignition power.
Pins 48, 52, 53 and 55 are constant battery power.
Pins 63, 65, 67 and 69 are grounds.
 
S

steevz

Active Member
Joined
Jul 16, 2012
Messages
31
Location
Vancouver, BC
Thanks for the info.

Luckily I don't need it, as the rear ECM plug is extremely difficult to get to, let alone probe.

The ECM harness between the inline fuse and a plug by the starter was losing 2.5v. By the time I removed the section of harness there was no continuity left in the power wire. Was rubbed through and corroded where the straps were holding the wires in the place.

Thanks for your help.


Sent from my iPhone using Tapatalk
 
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