Discussion:
F30 current limit problems

Hopefully someone else has run into this problem.

I've got a Cat F30 (5CB serial number) with low power to the drive wheels. The current limit is at 90 and 160 amps and causing low drive power. I cannot adjust the C/L any higher. The transistors are within tolerances and I even tried replacing them to see if it would make any difference. A rebuilt logic unit also don't show any difference. I used a Handyman to test all of the large diodes. High speed works fine when the 1A contact pulls in so I assume that the drive motors are ok.

Any suggestions on what could be wrong? Capacitor? Or driver board?
  • Posted 9 Mar 2009 14:24
  • Discussion started by sleepywheel
  • British Columbia, Canada
Showing items 1 - 4 of 4 results.
I was less worried about it going all the way down, as not coming all the way up, but if you see all the numbers in the on board testing with the drs switch, then I would be not spending much time concerned about the accel pedal. You should also be able to test the steering sensors board from the DRS switch and confirm the steering sensor is good all the way around.
  • Posted 10 Mar 2009 20:06
  • Modified 10 Mar 2009 20:09 by poster
  • Reply by edward_t
  • South Carolina, United States
edward_t - good thought about the accelerator pedal not going all the way down but everything passes the on-board diagnosis tests, which includes the accelerator test.

elektrodrive - the optical sensors are working since the directional contacts drop out and pull in at the right times. But i guess it can't hurt to lift the panel and do a quick inspection and cleanup of the eyes.

I think I'll try a driver board. The last F30 I worked on had drive problems and even though the driver board passed all the tests, it turned out to be the source of the problem.
  • Posted 10 Mar 2009 14:52
  • Reply by sleepywheel
  • British Columbia, Canada
Have you checked the steer sensor card on the back which i believe sits under the panel. It may think that its in a certain amount of lock and thus causing the motors not to run at maximum speed, Its worth giving the opto sensors a clear out with electrical cleaner. Also check motors.
  • Posted 10 Mar 2009 07:03
  • Reply by elektrodrive
  • West Midlands, United Kingdom
doesn't this have a drs switch, and have you tried to insure with the on-board diagnostics that the brake (wheel and park) switches are working, as well as insuring the accel pedal is working correctly?
  • Posted 9 Mar 2009 20:16
  • Reply by edward_t
  • South Carolina, United States

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