1998 fld120 12.7 ecm

Check grounds.

I have had a few 99/00's except the tach and Speedo all gauges are mechanical. However they could have been ordered either way.

Do you get a CEL/SEL with key on, no crank briefly?

 

You know it. The ground at the frame near battery box. Mine went bad. Looked good, no corrosion. Just cleaned it up, put some dielectric grease for good luck. Back in Business. Thanks to everyone on here helping me out.

 

Check engine light, Stop engine light.

If not verify power and ground to ecm. Voltage under 11.3 If I recall ecm will not turn on to protect it from low voltage.

I can not emphasize how important good clean grounds are.

 

Ok, so ecm is not powering up. You said you checked power wire, should be 2 actually. Did you check all grounds. Physically check/clean, ohm out cables?

Did you actually check voltage at ecm plug or assume its good from visual.

 

Also have a small inline blade fuse on one of the small power wires near the battery.

 

ECMs rarely go bad. You can take it off, open it up, and see if there’s any corrosion in it. Inspect the plugs. If it’s a ddec4, it has an internal battery. Sometimes they leak and corrode the soldered board connections. Just be sure to use good silicone when sealing it, and putting it back together. Won’t hurt to get 4 new rubber mounting bushings while you’re at it. If you decide to send it in, make sure they put a new battery in it, while it’s open. There’s probably nothing wrong with it. More likely a power wire or ground wire, if no cel lights on dash with key in on position. If lights were working, I’d say change timing sensors. I’m guessing the wires or fuse got disturbed when putting in new batteries, or fuse got blown from jump starting, or a shorted battery. I’ve had both issues with mine. .10 cent fuse, cost me a $500 towing bill to the Police pound.