I've got a Ford LRG 425 EFI with no spark. Power and ground to the epm no ground to the coil pack when cranking. Anyone have any ideas?
Does the coil pack have a red/green for power and a couple of yellow/? for timing? If so, the yellows switch ground when cranking to make the spark. A test light on one of the yellows should flash off and on when cranking and be accompanied by spark. The red/green should have ignition +12v.
Yes that's what the problem is they aren't getting ground.
If you probe one of the yellows, if it is not grounded, you will see +12v on it, flowing in from the red, through the coil and out the yellow looking for a ground. The controller provides that ground, so the yellow will be at 0v, and then when it wants the coil to fire, opens the circuit, which causes a spark and the yellow rises back to +12v for the dwell time, and then it grounds again. So you are saying the yellow is staying at +12v even while cranking? It could be a sensor problem, not seeing engine rotation, or it could be a controller just not doing its job.
Ok I get no voltage or ground at the yellow wires. Not trouble codes only 123
Does the red/green have +12v when cranking?
No
Did you get it figured out? I'm working on a JLG 600A lift with the same problem. I get a code also, similar to 123 like you're getting but the first short flash is not counted as a 1, it just means you are at the beginning of reading codes. The actual code is 23, "over maximum drive by wire" according to the Ford manual. I can only assume it's a TPS or governor problem but I'm not sure.
I believe "over maximum DBW" would equate to throttle position greater than 100%.
That's interesting, I assume the TPS operates using a 5v reference? Over maximum would suggest a voltage greater than 5V or whatever the base voltage is. Perhaps a wire rubbed through and is touching another wire? Or someone previously swapped a wire. I noticed my machine has a new cam sensor as well as a new crank sensor so they were troubleshooting it before I was lucky enough to acquire it.
Well, from what I've been reading in other LRG425 posts it would appear the 123 code is normal and does not indicate a problem.
I work on generators which run a fixed 1800 RPM and sometimes you will see throttle commanded to 102% so it may be normal in some cases. But I do not know about variable speed engines.