Archived Low voltage codes set...

[Weidner]

low voltage codes 122 apps, 236 map sensor, 522 oil pres sensor are set on my truck and it barley runs. Where should I look for the problem? I added a ground to the ecm and it ran in the garage, but would not on the road. That leads me to think it was a broke wire that maybe I jarred when I was adding the ground to the ecm housing. I have the ecm out and the wire loom spit appart and everything looks good. I have a new meter and tonight I am going to be checking wires for continuity. But I am really unsure of what to look for. I must have power to the ecm since it starts and idles. I am going to pin out the wires for the apps first and hope I find something wrong, but I don't think I will. All the conectors look good not a sign of corrosion anywhere. Also, the truc runs if I can get the cruise control set (if I can get it over 35 mph) I have the wiring diagram and nothing jumps out as the thing to check... anyone have some thoughts???

 

[chriscumminsdiesel]

Trying to find info for you. Code 122 is for intake manifold sensor. If this goes bad,truck will derate. Code 236 deals with Engine Position Sensor. Where did you read these codes from? I'm looking in the ISB T&R manual.

 

[Weidner]

Chris- As I understand it, code 122 is for the apps voltage too low. I have tested out the wires for the apps and map sensor, ecm power suppy, and ground and all look good. When I have the truck running I can get some different throttle response from it when I wiggle the harnes by the fire wall as I work the apps, thats why I think there is a short or broke wire. I am still checking the rest, but can't figure out what is setting these codes and making the truck run like crap. When I step on the throttle, no matter what amount, the response is slow rising rpm's up to red line, then when I let off it gives a little burst of rpms and then back to idle. I did not get my meter until tonight and I still have the truck appart with the ecm out. After testing the wires I am going to put it all back together and test the voltage at the map, throttle and oil pres senser. Maybe its a bad ecm, not sending enough voltage to the sensors, or maybe the ecm is not getting enough voltage... I can't figure it out.

 

[Weidner]

I gave up on it...

It was hard to do, but I managed to drive it all 26 miles to the shop using the cruise to maintain speed, since the throttle would not work. The dealer has it and I told them to remember its near Christmas and to be kind. I will report back when I know anything.

 

[TurboDog]

Please let us know the outcome. Thanks.

 

[Weidner]

New ECM fixed the truck. Cost a ton, works well. I guess that happens.