Fault Code 1117

[Rawze]

(08-24-2020 )DVT873 Wrote:  Rawze, had the same problem on a N14 a while back. Fuel solenoid feed from ECM. Realize that there may be an ECM problem. A "go time" issue. Ran keyed power out of the fuse box. Came off the solenoid with 2 diodes. Hooked keyed power to one and the ECM feed to the other. Figured if the ECM didn't see the solenoid it would get pissy. The diodes should stop any back feed. Didn't want key power going to ECM or ECM power going to key. Been a week or so. So far so good and no codes. Truck stays within 30 miles. Miss the simple days of turning the little knurled knob on the solenoid for bypass. Didn't need anything more than pliers if that.

The diode trick is short lived the way you have it hooked up.
You need a diode also in reverse across the pin to ground to bleed off the kick-back current from the coil. That kick-back current will go somewhere every time power is dropped off and if you have only forward facing diodes, it will jump internally across one of them and destroy one of both or the diodes after a while (and consequently, possibly the ecm ) after a while.

It can be done properly with 2 diodes, however it sounds like you did it wrong. ... one forward facing from the ecm... the other reversed across the coil power feed to ground... and the key-switch wired directly to the feed point of the coil (thru a 3a fuse of course).

Also.. diodes have a 0.7 volt drop across them. This could be a problem all in itself if your battery voltage is below about 13.3 or so.