I have three of these lifts, reach 740-R35TT serial numbers 250, 251 and 252(sister machines). I have one lift that was giving and intermittent code 57 for about 2 to 2 and a half days/shifts. It finally became a solid code and now is a dead machine. In the service manual it says the display module is recieving no communication from the VM. I ran the test checklist from the service manual (test I23 CAN BUS). All tests but one pass. The one test (test 3) that fails says to test the wires. The wiring tests good. 0.5 Ohms. It says if the wirinig is good then replace the LA (Lift Amplifier). So what I actually did was took the lift amp out of my dead machine and installed it in one of my live trucks. Works just fine in the live truck. When I take the VM out of my dead truck and install it in the live truck. Code 57 follows that VM and conversly when I install the VM from the live truck to the dead truck I don't get Code 57 but I get codes 5G and 5J.
Any help would be greatly appreciated.
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Alright - this issue got resolved. My vehicle manager was confirmed bad by the dealership. Purchased new vehicle manager(1200 USD), truck fired up but still code 5G and 5J instead of 57. Upon checking all the wiring, everything tested perfect from point A to point B, 0.5Ohms. The trouble was a bad pin on the connector to the lift amplifier for the CAN Bus signal(strange for this). The connector itself is all black plastic with a "red" push on connector housing. You can remove this housing to inspect the pins. We replaced the connector/housing and all the pins, dipped each pin in dielectric grease and plugged it back in. Truck runs fantastic now.
-Relays + relay card were good.
Hope this helps anyone in the future.
I should be able to check the relay card today or tomorrow. I'll let you know my findings.
First thing you do is look ay fuse relay card. Numero uno culprit for intermittant cut outs, codes 5G,5J. Remove the second relay from the left and look carefully at botton female slots. They may be fried, causing loss of current to VM. Remove the other relays and compare the female connectors to each other. They should be all tight together. Any discoloration or gap between pins indicates a new fuse card is needed. The relay will often appear burned as well. And always check for shorts to frame, battery voltage leak with an ampmeter. If the pins are just starting to get bad on the board, and the relay is fried, you can, as a temp repair, use the fourth relay on right and swap with the second one (after you cleaned the female pins) All your trucks will eventually fry the relay boards>>>
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