Error code 23 on a Raymond order or a Caterpillar order picker can be a tough code to solve.
It is almost guaranteed that the Q1 transistor must be replaced. After replacement, there are additional tests that need to be ran to determine the cause of the Q1 failure.
Possible Causes
- Worn drive motor brushes
- Dirty Commutator
- Deteriorated motor cables
- Binding drive unit
- Bad/shorted battery
- Bad Rectifier
- Caterpillar – Bad Chopper Module
| Code Title | Code 23 – Open Detected In Main Transistor Circuit |
| Reason | During SelfTest, proper current levels were not sensed by CT1 (on the Power Card) from the Power Transistor (Q1). Correct voltage not seen at Q1C sense. |
| System Response | |
| Alarm Sounds | Yes |
| Operator Display | Code 23. Inform Service |
| PC Contactor | De-energized |
| Speed Limit | 0 mph |
| How to Clear | If cycling the key switch OFF/ON does not clear this fault code, then follow the procedure below. |
| Tests to Run | Test A01 – Armature Sense Voltage Test A10 – Display Q1-C Sense Voltage (Page 6-124) Test O14 – Armature PWM Test (Page 6-205) |
Test A01 – Armature Sense Voltage
This test displays the voltage the Tractor Manager (TM) reads from the current sensor (CT) on the Power Card (at JS3-4).
The current sensor continuously monitors the current flowing through the drive motor adjusts its performance accordingly.
It is normal for the Power Card to go into current limit, particularly when accelerating. The Power Card’s current limit threshold is preset at the factory and is not adjustable.
For information on using Maintenance Mode, refer to page 3-19. This test can also be run from Active Maintenance.
Run test:
The Operator’s Display (OD) displays the voltage the TM reads from the current sensor.
The value displayed should be within 5.7 and 6.3V with the lift truck at rest. The reading should remain steady, and should not fluctuate by more than 0.02V.
- During acceleration, the voltage should increase.
- During deceleration (REGEN), the voltage should decrease.
The voltage should increase 1V per 100A through the armature of the traction motor. If these results are not observed, the test has failed.
It is normal for the Power Card to go into current limit, particularly when accelerating. The Power Card’s current limit threshold is preset at the factory and is not adjustable.
Diagnosis and Repair
Test A10 – Display Q1-C Sense Voltage
This test displays the voltage produced by the TM based on input from JPS14-9 (Q1-C Sense).
Run test:
The test is a success if the voltage displayed is within these limits:
| Test Setup | Voltage Displayed |
| All cables connected | 3.8 to 5.0V |
With the truck at rest, the reading should remain steady and not fluctuate by more than 0.2V. During Active Maintenance, the voltage on the OD should decrease as the speed of the truck increases.
Diagnosis and Repair
NOTE:
A failure in the Q1-C Sense circuit will not prevent Test O14 from functioning.
If Test O14 does not function, troubleshoot per the Diagnosis and Repair steps in Test O14.
Notes:
Test motor for over current also to be sure this is not the cause of the Q1 failure. If the motor is drawing 400-600A on a plug, it is probably bad.
Make sure the drive unit is not hanging up and causing a high amp draw on the drive motor.
Instructions For Installing The Updated Q1 Transistor
