Series 60 DDEC V Troubleshooting – Section 20.13 Fire Truck Pressure Governor Fault

Section 20.13
Fire Truck Pressure Governor Fault

The Pressure Sensor Governor (PSG) System is a DDEC feature, programmed to allow the engine speed to change in order to maintain a steady water pump pressure (pressure mode) or hold a steady engine speed (RPM Mode). ‪

Note: Most applications today incorporate the Detroit Diesel Electronic Fire Commander.

The following procedure will troubleshoot fire truck pressure governor fault.‪

Section 20.13.1
Verify Correct Pressure Sensor Governor Configuration

Perform the following steps to verify the PSG configuration. Refer to the Application and Installation manual to ensure correct inputs and outputs are configured. Required In / Outs are listed in Table "Required Inputs / Outputs" .‪

1. Turn ignition ON and plug in the DDR.
2. View H₂ O governor enabled (engine configuration).
3. View In / Outs. Verify correct configuration.
   1. If the system is enabled and the in/outs are correctly configured, refer to "20.13.2 Identify Problem" .
   2. If the problem was found, correct the settings and retest. Refer to the DDEC V Application And Installation manual, 7SA821.

   Inputs ‪		Outputs ‪
   PSG Mode, (Press / RPM)‪	Res / Accel‪	PSG Active‪
   PSG Enable‪	Set / Coast‪	Cruise Active‪

   Table 1. Required Inputs / Outputs
4. Using the DRS Select (PSG + Sensor Tab), verify that the water pump sensor has been configured correctly (V-29 – water pump pressure).
   1. If the water pump sensor has been configured correctly, refer to "20.13.2 Identify Problem" .
   2. If the water pump sensor has not been configured correctly, configure and test.

Section 20.13.2
Identify Problem

Use the following procedure to identify the problem with the PSG:‪

• Does not operate; refer to "20.13.3 Check System Ground" .
• No pressure mode, refer to "20.13.5 Verify Mode Selector Operation" .
• No increase function refer to "20.13.6 Check Resume / Accel Switch (Increase)" .
• No decrease function refer to "20.13.7 Check Set / Coast Switch (Decrease)" .
• EFC Fault Informationrefer to "20.14 Troubleshooting Electronic Fire Commander" .

Section 20.13.3
Check System Ground

Perform the following steps to check the system ground:‪

1. Start engine and turn ON pump control switch.
2. Verify all interlocks are set (parking brake, transmission neutral, etc.).
3. Plug in DDR. Select Switch/Light status.
4. Observe the displays and PSG ENABLE.
   1. If PSG ENABLE reads OFF, the PSG ENABLE input V-09 is not grounded. Check circuit V-09 for an open between battery ground or a short to a voltage source. Repair fault and retest. Refer to "20.13.4 Check Sensor Wiring" .
   2. If PSG ENABLE reads ON, refer to "20.13.6 Check Resume / Accel Switch (Increase)" .

Section 20.13.4
Check Sensor Wiring

Compare pressure sensor harness wiring to the diagram. See Figure "Pressure Sensor and Harness Connector" . If the EFC tests okay, refer to "20.13.5 Verify Mode Selector Operation" . If the wiring is incorrect, correct the wiring and retest.‪

Figure 1. Pressure Sensor and Harness Connector

Section 20.13.5
Verify Mode Selector Operation

Perform the following steps to identify the problem:‪

1. Start engine and turn ON pump control switch.
2. Verify all interlocks are set (parking brake, transmission neutral, etc.).
3. Plug in DDR. Select Switch/Light status.
4. Observe the displays and PSG MODE.
   1. If DDR displays ON when Pressure Mode is selected, the mode selector V-26 is functioning properly. Check for possible intermittent open or short to voltage source. Check for faulty pressure transducer. Refer to "20.13.4 Check Sensor Wiring" . See Figure "Pressure Sensor and Harness Connector" .
   2. If the DDR displays OFF when Pressure Mode is selected, the mode selector wire V-26 or switch is open or shorted to a voltage source. Repair the fault and retest.

Section 20.13.6
Check Resume / Accel Switch (Increase)

Perform the following steps to identify the problem:‪

1. Start engine and turn ON pump control switch.
2. Verify all interlocks are set (parking brake, transmission neutral, etc.).
3. Plug in DDR. Select Switch/Light status.
4. Observe the displays and Res/Accel, while pressing the increase switch.
   1. If DDR displays OFF to ON when increase is pressed, check the EFC.
   2. If the DDR displays OFF when increase is pressed, circuit V-08 is open or shorted to a voltage source. Repair the fault and retest.

Section 20.13.7
Check Set / Coast Switch (Decrease)

Perform the following steps to identify the problem:‪

1. Start engine and turn ON pump control switch.
2. Verify all interlocks are set (parking brake, transmission neutral, etc.)
3. Plug in DDR. Select Switch/Light status.
4. Observe the displays and Set/Coast, while pressing the decrease switch.
   1. If DDR displays OFF to ON when Set/Coast decrease is pressed, check the EFC.
   2. If the DDR displays OFF when decrease is pressed, circuit V-47 is open or shorted to a voltage source. Repair the fault and retest.