SPN 177 FMI 4 — Trans oil temperature voltage low
What it means: Trans oil temperature voltage low.
How serious / can you keep driving: Serious. Power derate likely — plan to stop soon.
Check first: Start with the most likely cause: Short ground.
Don't risk it — look up listed providers near you and give them this SPN/FMI when you call.
Listed providers nearest Phoenix, AZ
Closest first. Tell them SPN 177 FMI 4 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Phoenix, AZ · (623) 304-4187
- 0.0 mi away — based in Phoenix, AZ · (480) 458-7715
- 0.0 mi away — based in Phoenix, AZ · (480) 530-7347
Applies to: Volvo
What SPN 177 FMI 4 means
Trans oil temperature voltage low.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Short ground
FAQ
Trans oil temperature voltage low.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Short ground.
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside SPN 177 FMI 4, or share the same subsystem.
- Trans oil temperature very high (SPN 177 FMI 0)
- Trans oil temperature voltage high (SPN 177 FMI 3)
- Main shaft speed erratic (SPN 160 FMI 2)
- Input shaft speed erratic (SPN 161 FMI 2)
- Transmission output retarder speed erratic (SPN 162 FMI 2)
- Engine speed signal abnormal update rate (SPN 190 FMI 9)
- Transmission output shaft speed erratic (SPN 191 FMI 2)
- Output shaft speed abnormal (SPN 191 FMI 8)
Same symptom: Low oil pressure
Other codes a driver sees as an oil-pressure or oil-level warning.
- Trans oil pressure voltage high (SPN 1762 FMI 3) · Drivetrain & Transmission
- Trans oil pressure voltage low (SPN 1762 FMI 4) · Drivetrain & Transmission
- Engine Oil Pressure — Extremely Low (SPN 100 FMI 1) · Lubrication
- Engine Oil Pressure Too Low (P0524) · Lubrication
- Oil pressure sensor — voltage high (SPN 100 FMI 3) · Lubrication
- Oil pressure sensor — voltage low (SPN 100 FMI 4) · Lubrication
Find a mechanic or related guides
General diagnostic guidance for heavy-duty diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack). Not a substitute for a scan-tool diagnosis on your specific truck.