Discussion:
Cat F35 Line contactor problem

Hi there. I have been working on a cat F35 which does not have any plates with serial number or anything. Its the old F35 3 wheeler with twin motors. The problem I am having is:

Power up ok and if left on after a few minutes it just chatters the line contactor in and out until it eventually drops out the line and needs to be re set by the key switch in order for it to work again. If you turn it on and drive the truck or use the hydraulics it does the same thing, works for a bit then chatters the line until drops out again.

Its losing its negative to the line coil, however when I disconnect the negative feed off the coil and power the key on, the negative remains. Its only when the system is powered up with the line contactor coil connected this problem happens.

I had thought that if it was a logic fault then surely it would lose the negative supply with or without the line contactor coil connected, but not sure now as everything points toward this logic card.

I powered up the coil with a direct pos and neg to see if the coil was breaking down, but that seems to be ok. The coil remains powered up.

The negative into the card at the various pins remain correct. Can anyone help or has anyone come accross a similar problem. Have currently removed the logic and having it tested but would appreciate any comments.
  • Posted 2 Mar 2009 05:06
  • By elektrodrive
  • joined 2 May'08 - 739 messages
  • West Midlands, United Kingdom
Showing items 1 - 3 of 3 results.
Thank You
Had the card tested and have had it confirmed the fault is in the card. Hopefully after repairs should work fine.
  • Posted 3 Mar 2009 05:30
  • By elektrodrive
  • joined 2 May'08 - 739 messages
  • West Midlands, United Kingdom
If the drive system is cat micro command there should be a self diagonstics swithh inside the control card.You have to remove the main fuses to run the diagonstics.Throw the switch in the control card and start the test cycle.each test that passes will advance the display to a higher number and the last test will cycle the contactors.It has been a long time for me to test the micro command but try the self test with the main fuses in first.You cant hurt the card.you probably have a loose or dirty connection
  • Posted 3 Mar 2009 02:51
  • By howard_w
  • joined 28 Feb'09 - 7 messages
  • Colorado, United States
I had trouble with one of those a few years ago. I can't remember the exact symptoms but it would stop running after a short time. I finally found a bad connection in one of the wire harness plugs. It showed signs of overheating(plastic was melting) and I actually had to run a bypass wire around that pin on the plug. The harness plug was somewhere in the back by the control panel. Did you check all the harness plugs for bad connections?
  • Posted 2 Mar 2009 09:19
  • Modified 2 Mar 2009 09:20 by poster
  • By mrfixit
  • joined 11 Dec'08 - 1,434 messages
  • New York, United States

Post your Reply

Forkliftaction accepts no responsibility for forum content and requires forum participants to adhere to our rules of conduct. Click here for more information.

If you are having trouble using the Discussion Forums, please contact us for help.

PREMIUM business

GemOne
Telematics for industrial fleets. Fleet & safety management solutions: track vehicles, boost efficiency, operate safer, & avoid unexpected downtime.
Toyota 8FBE20U
Flesherton, Ontario, Canada
Used - Sale
Terberg YT220
Balling, Denmark
Used - Sale
Upcoming in the editorial calendar
WIRELESS CHARGING
Aug 2025
MANAGING MIXED FLEETS
Oct 2025