If the check-engine lamp is on and you do not have a scan tool, many late-model heavy-duty dashboards can still show active and inactive fault codes through the instrument cluster. The steering-wheel menu path — Menu / OK / arrow buttons — lets you open Diagnostics, Faults, or Service menus depending on the OEM.

This is not a full substitute for JPRO, INSITE, DiagnosticLink, or DAVIE. It is a fast field method to identify SPN/FMI pairs so you can decide whether the truck is safe to move, whether derate risk is rising, and which system to diagnose first.

Once you have the SPN/FMI, photograph the screen and upload it to AI Diesel Tech — or enter the code manually — to get a gated diagnostic sequence that prevents parts-cannon mistakes.

The steering-wheel diagnostic menu is available on most late-model heavy-duty trucks with digital instrument clusters:

Freightliner Cascadia (2008–present) — navigate to Diagnostics → Active Faults in the driver display.

Kenworth T680 / T880 — use the OK and arrow buttons on the steering wheel to reach the Faults menu.

Peterbilt 579 / 567 — same Paccar cluster as Kenworth; menu path is identical.

Volvo VNL (2018–present) — Driver Display → Service → Fault Codes.

Mack Anthem / Pinnacle — similar to Volvo; navigate to Fault Codes in the cluster menu.

International LT / RH / HV — use the steering-wheel controls to reach Diagnostics in the Driver Information Center.

OEMs added cluster diagnostics so drivers and technicians could identify inducement, derate, and stop-now conditions without waiting for a laptop or scan tool to be connected.

Federal emissions regulations require that drivers be notified of aftertreatment faults before inducement begins. The cluster menu gives technicians a fast way to confirm which SPN/FMI is driving the warning lamp and whether the truck is approaching a derate threshold.

For fleets, this means a driver can photograph the fault screen and send it to a remote technician before the truck even reaches the shop — saving diagnostic time and preventing unnecessary tows.

Not all trucks expose the full SPN/FMI list through the cluster. Some OEMs only show a generic "Engine Fault" message without the specific code.

No bi-directional tests are available through the cluster menu. You cannot command a DPF regen, test a solenoid, or read live data values.

Fleet telematics or body-builder settings may lock or restrict the diagnostic menus.

Cluster text is often abbreviated — "DEF Sys" instead of "SPN 5246 FMI 31." Always confirm the full SPN/FMI with a scan tool before ordering parts.

Inactive codes may not appear in all cluster implementations. If the lamp is off but you suspect a recent fault, a scan tool is required.

Never navigate the cluster menu while the truck is moving. Always park and set the brake before accessing diagnostic menus.

Do not clear fault codes without understanding what set them. Clearing a stop-engine code without diagnosing the root cause can result in engine damage.

If the cluster shows a red stop-engine lamp, do not move the truck until the fault is identified and cleared by a qualified technician.

Once you have the SPN/FMI from the cluster, AI Diesel Tech turns it into a gated diagnostic sequence — evidence-based tests ordered from cheapest to most invasive, with circuit proof steps before any parts are ordered.

Upload a photo of the cluster screen using DieselVision™ VIN Photo and AI Diesel Tech will extract the SPN/FMI automatically, even from glare-affected or angled shots.

The Technician Chat™ feature lets you describe what the cluster is showing and get an immediate answer on derate risk, safe-to-move status, and which system to test first.