Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 09, 2025 ...

ECM power

July 02, 2022, 08:23:14 pm

My books  are buried in bay. Does anyone happen to know where the power feed fuses are for the ECM on a 99-2000 ISC350. I see 2 fuse holders in the harness over top of the transmission. Any help would be appreciated. I'm 3800 into this deal and 700 miles from the shop that replaced the ECM. Now I have intermittent power code, Indicating a momentary loss of power on the battery hot to ECM.

Quote Selected

Re: ECM power

Reply #1 – July 03, 2022, 02:58:22 pm

A bad ground is one of the causes of ECU failure so you might check that. Easy for ground to be intermittent with fault in cable. Check that nothing is cutting into or crushing the injector wiring.

Pierce

Quote Selected

Re: ECM power

Reply #2 – July 04, 2022, 12:04:35 am

Bruce. Sorry your having issues. My 2001 ISM450 has the fuses were you mentioned yours were. Did you have intermittent power issues prior to ECM change? If no go back to were they changed the ECM plugs and double check they are secured. If they look good I would pull the plugs and visually check for a pushed pin in the connector. Putting a jumper across any suspected wire with a light bulb in series will indicate when you are not getting good connections. This also works on the ground wire like Pierce mentioned. Grounds can be elusive to track down. Wish I could offer more.
Scott

Quote Selected

Re: ECM power

Reply #3 – July 04, 2022, 12:19:09 am

You might also check the alternator wiring to make sure none of the connections look overheated and are secure. Check connections at isolator if you have one. Engine battery terminals/connection may be suspect even though diesel is starting OK. Any loose connections can result in a voltage spike that ECUs don't like. Changing resistance at the engine batteries can let the alternator rapidly change voltage output. Do you have the ECU history with any current or past fault codes?

Pierce

Quote Selected

Re: ECM power

Reply #4 – July 04, 2022, 09:56:05 am

Checking all the hots and grounds, fuses and fuse holders in the wiring harness, and frame grounds

Quote Selected