Signs you need a proper diagnostic, not just a scan
- A warning light that comes back within days of being cleared elsewhere
- Intermittent faults that never show while the truck is at the workshop
- A part has already been replaced based on a code, and the problem is still there
- The truck goes into limp mode occasionally but drives fine most of the time
- Multiple warning lights appearing together, suggesting a shared power or network fault
- Electrical gremlins after fitting accessories, a tow bar or a stereo
What we diagnose
- Check engine, ABS, traction and airbag warning lights
- Limp mode and reduced power events
- Intermittent electrical faults, parasitic battery drain and charging issues
- DPF, EGR, SCR and AdBlue system faults on diesel trucks
- Transmission fault codes and shift quality complaints
- Module coding, programming and calibration after component replacement
- Pre-import and post-conversion electrical gremlins
Common faults by brand
RAM Cummins and Hemi/eTorque
6.7 Cummins trucks commonly throw codes for EGR cooler restriction, DEF quality/dosing faults and turbo actuator position errors. eTorque Hemi trucks frequently present as a rough idle, delayed stop-start restart or a charging warning that traces back to the 48-volt mild-hybrid battery rather than the main 12-volt battery — a distinction a generic scan tool won't make for you.
Silverado, GMC Sierra & Denali (Duramax & L87)
Duramax trucks often show DEF system, glow plug module or fuel rail pressure codes. Petrol L87 engines with Active Fuel Management/Dynamic Fuel Management are prone to lifter-related misfire codes and a characteristic tick on cylinder deactivation — a well-known issue on this platform that generic diagnostics frequently misreads as a spark or fuel problem.
Ford F-Series (Power Stroke & 10R140)
Power Stroke diesels commonly present turbo boost, EGR and DEF codes, while 10R140-equipped trucks can show shift quality complaints tied to adaptive learning after a battery disconnect or towing overheat event — often solved with a proper relearn rather than parts.
How our diagnostic process works
- 1Full system scan and freeze-frame data capture across every module.
- 2Live data and road test under the conditions where the fault appears.
- 3Circuit-level testing — we test the wiring and the component, not just the code.
- 4Written findings with the root cause, the repair options and a quote before work starts.
A fault code names a circuit, not a broken part. Replacing the part a code mentions is the single most expensive mistake we see on American trucks.
Why generic scan tools fall short
A generic OBD reader sees emissions-related engine codes only. It cannot read body, chassis, transfer case, trailer brake, air suspension or telematics modules, cannot perform bi-directional tests, and cannot code a replacement module to the vehicle. On a US truck with 30-plus networked modules, that is a small fraction of the picture.
Scan tool comparison
| Generic OBD reader | Manufacturer-level diagnostic equipment | |
|---|---|---|
| Reads emissions codes | Yes | Yes |
| Reads body/chassis/transfer case modules | No | Yes |
| Bi-directional component tests | No | Yes |
| Module coding after replacement | No | Yes |
| Circuit-level wiring diagnosis | No | With additional testing |
How long does diagnosis take, and what does it cost
Straightforward fault codes can often be assessed within an hour. Intermittent electrical faults that only appear under load, heat or vibration can take considerably longer because we need to reproduce the condition. Diagnostic time is charged and quoted before we start, and you get a written finding plus a repair quote before any further work begins — we don't invent a price up front because every fault is different.
Towing, touring and Queensland conditions
Heat, dust and vibration from corrugated tracks or long tows are common triggers for intermittent connector and sensor faults that never show up parked in a driveway. If a warning light only appears towing up the range or after hours on dusty hinterland roads, tell us — it helps us reproduce the fault on the road test rather than chasing it on the hoist.
Frequently asked questions
- How much does diagnostics cost?
- Diagnostic assessment is charged by time and quoted before we start. We give you a written finding and a repair quote at the end of the assessment so you can decide with all the information — there's no single fixed diagnostic price because faults vary widely in complexity.
- My truck is in limp mode — can I drive it in?
- If the truck is safe to move at low speed, yes. If it will not hold speed on the highway or has an active safety fault, call us on 07 5491 2199 and we'll advise on towing it in.
- Why does my warning light keep coming back after being cleared?
- Clearing a code doesn't fix the underlying fault, only the flag. If the root cause — a failing sensor, a wiring issue or a mechanical fault — isn't repaired, the light will return, often within the same trip or a few days of driving.
- Can you diagnose electrical problems after I've fitted accessories?
- Yes. Aftermarket wiring is one of the most common causes of intermittent faults on American trucks with sensitive body control modules. We circuit-test the accessory wiring alongside the factory system to find where the fault actually lives.
- Do you do diagnostics near me if I'm not from Caloundra?
- We're based in Caloundra on the Sunshine Coast and regularly diagnose RAM, Silverado, GMC and Ford F-Series trucks for owners travelling from across the wider Sunshine Coast region.
- Can a generic scan tool diagnose my Silverado's misfire?
- Not fully. A generic reader may show a misfire code but can't access GM-specific live data for Active Fuel Management/lifter faults or run bi-directional tests to confirm which cylinder and component are actually at fault.
- What causes repeated DEF or AdBlue faults on diesel trucks?
- Common causes include DEF quality issues, a failing dosing module, a blocked injector or a faulty NOx sensor. We test the system rather than replacing the DEF tank sensor by default, which is the most commonly misdiagnosed part.