Volvo VNL D13 MID 128 SID 232 FMI 4 - 5 Volt Reference low

Question

My 2014 VNL is throwing a MID 128 SID 232 code and the dash is lit up with multiple sensor faults. The truck is in derate and showing low oil pressure and crankcase pressure errors simultaneously. I suspect a short in the 5V reference circuit but I am not sure which sensor is pulling the voltage down.

garagegrease · Accepted Answer

Found the issue at the Crankcase Pressure sensor harness. The wiring had rubbed through against the alternator bracket, causing a direct short to ground on the 5V reference wire. I cut out the damaged section, soldered in a new pigtail (part number 21013444), and re-loomed it with high-temp heat shield. Total cost was about $45 in parts and 3 hours of diagnostic time. The 5V supply stabilized at 4.98V immediately after the repair.

hd_trucker_77 · Answer

Use a multimeter at the EA connector and check for continuity to ground on the 5V supply pins. If you have less than 10k ohms to ground with the sensors unplugged, you definitely have a harness rub-through.

obd2_owl · Answer

Check the wiring harness where it crosses over the top of the valve cover. These D13 looms are notorious for rubbing through on the metal P-clamps and grounding out the reference wires.

Jake Morrison · Answer

SID 232 usually refers to the 5V reference bus inside the engine harness. Since you have multiple sensor codes, start by unplugging the Oil Pressure sensor and the Crankcase Pressure sensor one by one to see if the 232 code becomes inactive.

Volvo VNL D13 MID 128 SID 232 FMI 4 - 5 Volt Reference low

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