Before anything else: if steering weaves or reacts slowly, check the machine. Play in the steering linkage, tired hydraulics and low tire pressure will beat any setting change — auto-steer can't fix a worn machine. With that out of the way, here's the order we go through on the phone when SmarTrax won't engage.
1. GPS has to reach the SmarTrax node
The node steers off GPS it receives directly, not off the display. With an external receiver, the chain is: receiver output → SmarTrax node (or control box DGPS input) → node output (or the control box Lightbar port) → field computer DGPS input. With internal GPS: field computer output → node input → node output → field computer input. Then check the GPS source setting on the display: Viper Pro = Generic GPS; Envizio Pro = Internal via Tilt or SmarTrax; Viper 4 = SmarTrax GPS on DGPS.
2. NMEA messages and baud rates
The node wants GGA at 10 Hz, VTG at 10 Hz and ZDA at 0.2 Hz. Baud rates must match on both ends: receiver output to SmarTrax at 19200 with the GPS baud in the SmarTrax settings also at 19200; SmarTrax output to the field computer at 115200. NMEA at 5 Hz limits a stand-alone system to roughly 10 mph, so a slow receiver shows up as a speed problem.
3. Watch the switch status change
Press the foot switch or steering switch and watch the status on the display. On the long-box controller, "foot swtch / steer swtch" go upper-case when pressed; Envizio Pro and Viper 4 show green versus red; Viper Pro shows upper versus lower case. If nothing changes, it's the switch or its wiring — not the node.
4. Are you inside the speed window?
- Engage: stand-alone controller 1.5–14 mph; CAN SmarTrax below firmware 7.4, 1.5–14 mph; CAN SmarTrax 7.4 and newer, 0–18 mph (SmarTrax MD must engage above 2 mph); RS1, SC1 and TC1 engage from 0 to 18 mph.
- Too slow: stand-alone and CAN SmarTrax stop steering below 1 mph and disengage after 7 s (stand-alone and CAN before 7.4) or 20 s (CAN 7.4+). RS1/SC1/TC1 disengage after 30 s below 0.34 mph (0.045 mph on RTK).
- Too fast: 27 mph for CAN SmarTrax and RS1 (22 mph on stand-alone firmware 2.1 and older) triggers the "Too Fast" alarm, disengages after 5 s, and disengages immediately 1 mph over that. RS1 and SC1 cut out at 29 mph; TC1 tops out at 12 mph.
- Reverse steering works inside those same windows, but not on articulated machines.
It engages, but weaves
- Slow, gradual weave: verify the antenna fore/aft measurement; raise the PWM values 1–2% at a time; raise On-Line sensitivity (OL) 1–2 at a time, waiting 30–40 seconds between changes; inspect the steering sensor; look for mechanical play.
- Jerky weave: sensitivity or PWM Min is too high. PWM Min normally lives at 20–40%; above 40% is suspect — lower it 1–2% at a time, and lower OL 1–2 at a time.
- Won't get onto the line: Line Acquire (LA) too low — raise it 1–2 at a time, and point the machine down the line before engaging. Over-steers onto the line: LA too high — lower it.
LA works beyond 24–36 inches from the line; OL works inside that. A good calibration on flat, firm ground beats all of the tuning above.
The 3D calibration trap
Never cancel the 3D compensation step. A cancelled 3D cal is stored as complete, works fine on flat ground, and goes badly in rough terrain. Envizio Pro/Cruizer II: Tools > Steering > 3D Setup > Calibrate 3D. Viper 4: SmarTrax > 3D Comp > Calibrate. Viper Pro: SmarTrax box > 3D Setup > Calibrate 3D. If a line jumps mid-job on a SmarTrax machine, bypass 3D — if the jump stops, the node needs repair.
SmarTrax MD error messages, quick reference
- HC Volt H / HC Volt L — supply over 16 V or under 10.6 V: check battery voltage and connections.
- HS Fail / No HC Sync / Torque H — mechanical drive hardware (Torque H is over 8 A — check for binding first). On the Manual Steering screen, toggle the master switch, drive the motor and watch Actual Current; no current means the drive is replaced.
- MsSw Off — the switch under the MDU is off. Oper Error / OpSW Fail — presence switch disconnected or out of the seat: check the connection.
RS1 tuning order, RS1 lights and DTCs, and the steering sensor and valve voltage tests are in the Raven Troubleshooting Guide. We stock Raven steering kits, sensors and cables — or call (509) 838-2209 and we'll walk it with you.
Procedures summarized from Raven's Interactive Troubleshooting Guide and Raven Support Center articles. Confirm against the manual for your hardware and software version. Spray Center Electronics is an independent Raven dealer in Spokane, WA.