Cat Lift Trucks (& Caterpillar) NR3500:
K2 contactor not comming in properly

When first turn key on to power unit up horn cycles on and off dash dont power up properly. Have noted the K1 comes in fine k2 does not if run key switch a couple times truck will power up properly I have battery voltage to both contactors but the negative does not test like a true negative on either contactor weather it works or not. I was advised to changeand I have changed both k1 and k2 contactors have checked all wire connections the control wires come from the a1 and a2 controllers. Is this a controller problem?can I take the negative signal from k1 and use it for the k2 in order to get this unit to power up correctly
  • Posted 1 Oct 2014 03:46
  • Discussion started by Kurt
  • Wisconsin, United States
Showing items 1 - 6 of 6 results.
I think the K2 negative is provided by the AC2 controller. I would check the key and e-stop contacts with your meter. These are a common failure. Make sure and disconnect the battery and test the truck side connector to frame for shorts. As swoop223 stated the key switch powers the dash. You may have a dash display failure if all you wiring connections check out.
  • Posted 3 Oct 2014 13:27
  • Reply by shovel_fx
  • Illinois, United States
best i can tell from the wiring schematic those 2 relays you speak of K11 and K12 which are listed as K31 and K32 in the schematic are for the horn and travel alarm. The reason the K12 (K32) relay is not pulling in is because the settings in the programming are probably turned off so the relay is rendered inactive untill one of the travel alarm settings is set.

my best guess about this

now as for the contactor when the system is turned on it tells logic to supply negative to the K11 coil and to the horn circuit side of the relay.

as for the display it gets its positive power from the keyswitch circuit directly. Negative is fused with a 2A fuse.
Since your getting intermittant display power you may want to pull the display panel and check all the connectors, check the fuses in the fuse strip and make sure both circuits on the keyswitch are working properly, it is double pole switch.

The only other issue i can think of would be some issue with the logics.
  • Posted 2 Oct 2014 11:53
  • Modified 2 Oct 2014 11:55 by poster
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com
The only fault was and or is when the k2 contactor does not pull in is the code telling me that contactor is the problem and thats why i was advised to change contactor nothing in fault history
  • Posted 1 Oct 2014 22:55
  • Modified 2 Oct 2014 03:03 by poster
  • Reply by Kurt
  • Wisconsin, United States
is it showing any codes on display?
if you have access to the service menu you can look at the fault history and see whats been going on with the truck and the hours when it occurred.
usually when there is a fault with these trucks it will beep and a fault light will show up along with a display code. Since you say the display is not coming up properly you will have to either check the history once it does come up (since you say it does randomly) or you will need the zapi handset or the pc tool to get an idea of what is happening when it starts and faults out.
  • Posted 1 Oct 2014 22:50
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com
Serial number: 4NR3524715
Model number: NR3500
This entire unit is A/C it has zapi controllers
  • Posted 1 Oct 2014 21:22
  • Reply by Kurt
  • Wisconsin, United States
Kurt
can you give us the full model and serial number of this unit?
  • Posted 1 Oct 2014 20:40
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com

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