K10 will not close until the truck is activated. If you are getting C28 K10 will not close.

You will need to test the CAN bus lines from the traction amp to the display unit. J5-1 (CAN_HIGH), J5-8 (CAN_LOW) at the traction amp and A2-3 (GRN CAN_HIGH), A2-7 (WHT CAN_LOW) at the control head.

If can bus tests ok then I would suspect you have a failed traction amplifier.

J5-16 has 23.4 volts with master on I don't hear main contact close.

After reading the manual I think it's as simple as a main contact. I was assuming that because the c28 code the main contact would not close. But after reading the schematics and reading that you need to turn the master on first then switch the key on. Not familiar with Raymond's but learned a lot.

Sounds correct, you will have a slight voltage drop from B+ after the R1.

Do you have B+ at J5-16 at the traction amp with S21 (Main on/off switch) closed and key switch open?

I didn't ohm out the r1 but I have 25.4 volts before r1 and 23.2 after.

1. Main ON/OFF switch not activated when the key switch was turned ON.
2. Low voltage to the traction power amplifier (especially while lifting or driving)
due to over-current or short-circuit.
a. Try a known-good battery.
3. PTC R1 missing, faulty, or tripped (should be 18 ohms).
Note: A very high resistance is possible due to excessive current while the main
contactor is open. It should automatically recover.
a. Carefully check to see if R1 is hot (tripped). If so, unplug the battery and
allow it to cool. Locate the low impedance path that tripped R1 and correct.
4. Check the K30 Relay.
5. Wire #24 near 0V.
a. Check that J5 is connected, check the fuse, and check the wiring.
6. Check for Shorts to frame.
a. Check for 24V at J5-16.
7. Short or open circuit in the CAN wiring, or electrical noise in the CAN wiring
due to a bad connection or outside interference, both at power-on.
a. Check the CAN wiring.
8. Faulty traction power amplifier.
a. Check the power wiring.