The Curtis 1243 MultiMode controls electric trucks and other industrial vehicles with a separately excited DC motor. It is not an AC controller. This guide condenses the fault codes from the Curtis manual and shows how to read the fault history.
What the Curtis 1243 is
The 1243 regulates armature drive and braking current and drives the field through a full bridge, so no direction contactors are needed. The manual gives nominal battery voltages of 24 V and 36 V.
| Model family | Battery voltage | Armature rating 2 min | Armature rating 1 h |
|---|---|---|---|
| 1243-24XX | 24 V | 350 A | 120 A |
| 1243-42XX | 24 to 36 V | 200 A | 80 A |
| 1243-43XX | 24 to 36 V | 300 A | 100 A |
The last two digits tell the generation. 1243-2401, 1243-4202 and 1243-4301 are original 1243 controllers. 1243-2420, 1243-4221 and 1243-4320 are 1243GEN2 controllers. The codes below come from the GEN2 manual. For an older controller, check the codes against Curtis documentation for your type.
How the controller reports a fault
There are four channels. The handheld programmer shows plain text. The optional Spyglass display shows the same code as a number, so 3,2 appears as CODE 32. The status LED sits under a window in the label on top of the controller. Two fault outputs feed dash lamps.
With no fault, the status LED blinks a single even flash. With a fault, it repeats a two digit code. The first number is the flash group, and after a pause comes the second number. Code 3,2 looks like three flashes, a pause, then two flashes. The controller reports only one fault at a time. An LED that stays off means no power or a defective controller. A solid LED means a controller or microprocessor fault.
Fault code table
The last column paraphrases the manual. Operational faults such as a wrong switching sequence clear when you cycle the interlock or the keyswitch (KSI).
| LED code | Programmer display | Meaning | First check |
|---|---|---|---|
| 0,1 | NO KNOWN FAULTS | Controller operating, no faults | none |
| 1,1 | CURRENT SHUNT FAULT | Current sensor error | Cycle KSI. If it persists, replace the controller. |
| 1,2 | HW FAILSAFE | Hardware failsafe triggered | Look for electrical noise, cycle KSI. Then replace the controller. |
| 1,3 | M- SHORTED | M- shorted to B- | Check motor wiring, cycle KSI. Then replace the controller. |
| 1,4 | SRO | Static return to off active | Follow the sequence of KSI, interlock and direction. Check interlock and direction switches. |
| 2,1 | THROTTLE WIPER HI | Throttle signal too high | Check the wiper wire for an open circuit or a short to B+. Check the pot and the selected throttle type. |
| 2,2 | EMR REV WIRING | Emergency reverse wiring check failed | Check the emergency reverse and check wires for an open circuit. Re-apply emergency reverse or cycle the interlock. |
| 2,3 | HPD | High pedal disable active | Follow the sequence of KSI, interlock and throttle. Check the pedal and parameters. |
| 2,3 | SRVC TOTAL, SRVC TRAC, TOTAL DISABLED, TRAC DISABLED | Service or disable timer expired | Perform the service and reset the timer with the programmer. |
| 2,4 | THROTTLE WIPER LO | Throttle signal too low | Check the pot wire for an open circuit or a short to B+. Check the pot and throttle type. |
| 3,1 | FIELD SHORT | Contactor coil or field winding shorted | Check the contactor coil and field winding, including shorts to B+ or B-. |
| 3,2 | MAIN CONT WELDED | Main contactor welded | Check wiring and the main contactor. |
| 3,3 | FIELD OPEN | Field winding open | Check field terminals S1 and S2 and the winding. |
| 3,4 | MISSING CONTACTOR | Main contactor missing or coil open | Check coil, contactor and supply wire. |
| 4,1 | LOW BATTERY VOLTAGE | Battery voltage too low | Check battery condition. Fix corroded or loose terminals at battery and controller. |
| 4,2 | OVERVOLTAGE | Battery voltage too high | Check whether the vehicle ran with the charger connected. |
| 4,3 | THERMAL CUTBACK | Output reduced by over or under temperature | Check load and mounting. The manual names above 85 °C and below minus 25 °C. It clears when the heatsink is back in range. |
| 4,4 | ANTI-TIEDOWN | Mode switch held or shorted to B+ | Release Mode Select 1 and check the switches and wiring. |
| 4,4 | MOTOR HOT, MOTOR WARM | Field resistance above setpoint, motor too hot | Let the motor cool and check the load. |
Codes 3,2 and 3,4 only occur when the contactor diagnostics parameter is switched on. Codes 3,1 and 3,3 depend on the field check parameter.
Fault outputs for dash displays
In code format, Fault 1 flashes the same code as the LED, and Fault 2 pulls low on any fault. In category format, both lines together signal one of four groups.
| Fault 1 | Fault 2 | Category | Faults included |
|---|---|---|---|
| High | High | 0 | no fault |
| Low | High | 1 | current sensor, failsafe, M- short, throttle, emergency reverse, field, contactor |
| High | Low | 2 | undervoltage, overvoltage, temperature |
| Low | Low | 3 | anti-tiedown, HPD, SRO, timers, motor too hot |
Reading faults with a handheld programmer
The handheld programmer plugs into the controller's four pin programmer connector and takes its power from there. Unplug a Spyglass first. Plug the device only into a Curtis programmer port, because other voltages can permanently damage it.
- Connect the programmer and switch the keyswitch on. The device starts, and the status LED blinks one even flash.
- On a 1311, open the Faults menu. System Faults shows current faults and Fault History shows the log. Faults appear as a code with text.
- On a 1313, open the Diagnostics app. Present Errors shows existing faults. Fault History lists everything since the last clearing, with the newest entry shown as 1 of x.
- The Monitor menu shows live values such as battery voltage, heatsink temperature and field and armature current. On the older 1307 it is called the Test Menu.
- Clear the log only after the repair. On a 1311 use Clear Fault History and confirm. On a 1313 use the Clear All softkey, which appears only while the Fault History folder is highlighted. Single faults cannot be cleared.
Curtis recommends checking the history at every service visit. After clearing, a later look shows whether the repair worked. Faults can be one-off events, so cycle power before replacing parts. Four programmer access levels decide which values are visible.
Safety during diagnosis
For the functional check, the manual requires the drive wheels to be raised off the ground. Nobody may stand in front of or behind it. Wear safety glasses and use insulated tools. The controller has no serviceable parts and must stay closed.
For cleaning, disconnect the battery and discharge the controller capacitors through a load across B+ and B-, for example a contactor coil or a horn, as the manual describes. Tighten the M8 bus bar bolts to 16.3 N·m at most. Follow the vehicle manufacturer's instructions.
Matching parts from the catalog
Check the fit against nameplate and part number before ordering.
The original 1243 is listed as 1243-2401 for 24 V and as 1243-4202 and 1243-4301 for 24 to 36 V. The second generation is available as 1243-2420, 1243-4221 and 1243-4320.
Reading faults needs a programmer. The handheld 1311-2201 is the older type. According to Curtis, the 1313-2131 replaces it with more functions. For a PC, use the kit 1314K-2201, which includes a USB interface and a Molex cable.
FAQ
What does code 3,2 mean on the Curtis 1243?
Code 3,2 means a welded main contactor. According to the manual, the cause is a contactor stuck closed or a shorted contactor driver. Check wiring and contactor, then cycle the keyswitch.
How do I clear a fault on the Curtis 1243?
Operational faults such as SRO or HPD clear with the correct switching sequence or by cycling interlock and keyswitch. You empty the fault history with the programmer once the cause is fixed.
Can I read the faults without a programmer?
Yes, through the status LED flash codes or an optional Spyglass. The history of earlier faults and the monitor values need a programmer.
Need one of the parts mentioned? We deliver the matching part with a quote on the same day, and express shipping is possible.