Cub Cadet 2000 Series - Manual (Page 91)

Electronic Power Steering
85
9f. Without sitting on the tractor, turn the steering wheel a quarter turn back and forth. Watching the voltage
reading on the DMM and the current reading on the amp clamp while doing this.
NOTE: If the voltage drops below 13 volts and the current does not rise above 10 amps, repair the circuit sup-
pling voltage to the EPS before proceeding with troubleshooting the EPS system.
NOTE: If the voltage drops below 13 volts and current draw is more than 10 amps, the problem is inside the
EPS assembly and it must be replaced.
9g. Turn off the tractor.
10. Check the input from the ignition module.
10a. Connect the ground lead of an oscilloscope to a
good ground on the engine block.
10b. Back probe EPS harness connector at the yel-
low wire with a white trace using the positive (+)
lead of the oscilloscope.
10c. Start the engine.
11. The oscilloscope should show a pulsed signal. The
bottom or resting phase of each pulse must be below
5 volts. The peak of each pulse must be over 5 volts.
See Figure 6B.9.
12. The pulses must be at 9 Hertz (cycles/second) or
higher (engine needs to be >490 RPM).
13. If the resting phase of the pulse is above 5 volts,
there is a short in the safety circuit of the tractor that
is pulling up the voltage of the ignition module.
NOTE: A voltage spike over 18.5vdc +/- 1.2v @70°F will cause the voltage regulator to shut down. The regula-
tor must be disconnected, then re-connected to reset it.
NOTE: A sustained voltage over 25 volts will damage the EPS module.
NOTE: If the results are within the specified ranges or if the amperage draw is higher then expected, check for
a mechanical bind by:
14. Remove the steering pinion gear by following the procedures described in Chapter 6A: Steering.
15. Re-check the steering.
NOTE: If the steering now works, the problem lies between the sector gear and the front wheels. A frozen axle
is a likely suspect.
16. Remove the EPS assembly.
NOTE: When removing the EPS from the steering housing, it should slide out easily. If it does not, repair the
steering housing before condemning the EPS.
17. Check the steering shaft bushings.
NOTE: If the steering shaft is binding in the bushings, replace the bushings before condemning the EPS.
18. If nothing is in a bind, replace the EPS assembly.
Figure 6B.9
5 volt
reticle