More Volvo nightmares. Code: MID130 SID251 FMI5

Greetings, I'm here again with more electrical problems. The truck is a 2004 VNL 630, D12D 465 with Eaton RTO1691C-AS2 auto-shift transmission. Occasionally the trans will miss a shift, then find it. When I check the diagnostics, there's an inactive code MID130 SID251 FMI5. As best I can decipher, the code is for transmission ECU power supply. Yesterday morning the code was an active fault and the truck would'nt start. When I finally did get it started, it would not shift right. later in the day it was ok. I think I'm intermittently losing power to the TECU. I have 3 power leads coming from the batteries. I think one is the engine ECU, one is trans ECU, and I'm not sure what the third would be. I guess my question is; can I buy the TECU power supply harness or just try to find and fix whats wrong? Any help would be greatly appreciated. Thanks

 

I think I can, I think I can, hehe. I was under there today. I saw which power lead was to the engine and trans ECU's. The third lead is to the Wabasto bunk heater. Although I didn't find any problem as far as I could see, I did remove and clean all the cable ends. I will next take the batteries out to see if it will give me more access to trace it all the way to the TCU. Thanks for the reply.

 

Thanks @nasriza How much trouble is it to replace the harness? There appears to be an access panel in the floor. Any special procedures to doing this job? Thanks for you help and the reply.

 

Thanks. I kinda thought that the floor covering would have to be removed or the seats taken out to access the panel. There is a local shop here that has done them before, so I decided to let him do it. I'm just no good in tight spaces anymore. He said 2-3 hours labor. No one close by stock the harness. So Transource in Raleigh ordered one.. $450 includes overnight shipping.