Engine Protection System Circuit Diagnosis. GMC Truck Savana 1999

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1999 🢒 Savana 🢒 Engine 🢒 Engine Controls - 6.5L (L65) 🢒 Engine Protection System Circuit Diagnosis

Circuit Description

The engine protection system utilizes a separate control module and independent sensors to monitor the oil pressure, coolant temperature and coolant level. With each engine start up, the system self tests with an alarm and light display for 3 seconds. When the engine is started, the alarm and light display will cancel as oil pressure rises. When a malfunction occurs (engine coolant overheat, low coolant level, or low oil pressure), the engine protection module will open the engine shut off solenoid (ESO) located on the injector pump 30 seconds after the condition is detected.

Diagnostic Aids

The following conditions may cause a no start or false alarms:

•	If the engine protection module in-line fuse, located under the dash near the module is open, the engine will not start.

•	The engine protection module ground has a poor connection.

•	A wire to the coolant level sensor that is broken inside the insulation may cause an intermittent alarm

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

This step verifies the engine protection system is functioning.

This step checks the low oil pressure circuit for a short to ground.

This step checks the high engine temperature circuit for a short to ground.

This step checks the low coolant sensor circuit for an open.

Step

Action

Value(s)

Yes

Important: Before clearing the DTCs, use the scan tool Capture Info to save the Freeze Frame and Failure Records for reference. The control module's data is deleted once the Clear info function is used.

Was the On-Board Diagnostic (OBD) System Check performed?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Attempt to start the engine.

Does the engine start and then stall after 30 seconds?

Go to Step 3

Go to Step 4

Is the engine protection system shutdown lamp ON?

Go to Step 5

Go to Step 4

Is DTC P0215 set?

Go to the applicable Table

Go to Step 16

Turn the ignition ON.
Start and idle the engine.
Monitor the following status lamps:

•	Low coolant level

•	Low oil pressure

•	High engine temperature

Is the low oil or high engine temperature lamp on before the engine shutdown occurs?

Go to Step 6

Go to Step 7

Is the low oil lamp on?

Go to Step 8

Go to Step 9

Check and fill the coolant surge tank to the proper level.
Start and idle the engine.

Is the low coolant lamp on before the engine shutdown occurs?

Go to Step 13

Go to step 22

Disconnect the low oil lamp switch for the engine protection system.
Turn the ignition On leaving the engine OFF.

Is the low oil lamp ON?

Go to Step 10

Go to Step 11

Turn the ignition OFF.
Disconnect the high engine temp lamp switch.
Turn the key ON leaving the engine OFF.

Is the high engine temp lamp ON after 30 seconds?

Go to Step 12

Go to step 17

Turn OFF the ignition.
Verify the oil pressure switch is disconnected.
Disconnect the engine protection system module.
With an J 35616-200 unpowered test lamp connected to voltage, probe the oil pressure harness connector.

Is the test lamp ON?

Go to step 20

Go to step 19

Start and idle the engine, monitor the oil pressure gauge ( in dash).

Is the oil pressure more than the specified value?

10 psi

254 kPa

Go to step 15

Go to Oil Pressure Diagnosis and Testing in Engine Mechanical

Turn the ignition OFF.
Verify the high engine temperature switch is disconnected.
Disconnect the engine protection system module.
With an J 35616-200 unpowered test lamp connected to voltage, probe the high engine temp switch circuit at the high engine temp harness connector

Is the test lamp ON?

Go to step 21

Go to step 19

Disconnect the low coolant probe.
Use a fused jumper and ground the low coolant harness connector.
Turn the ignition on leaving the engine off.

Is the low coolant lamp ON?

Go to Step 14

Go to step 18

Check the low coolant lamp circuit for the following conditions:

•	An open wire

•	Proper connection to the engine protection system module.

If the low coolant lamp circuit problem is found, repair the circuit as necessary. Refer to Wiring Repairs Wiring Repairs in Wiring Systems.

Is the action complete?

Go to step 22

Go to step 19

Replace the oil pressure switch for the engine protection system. Refer to Engine Protection System Oil Pressure Switch Replacement .

Is the action complete?

Go to step 22

Connect the scan tool.
Start and hold the engine between 2000 and 2500 RPM.
Monitor the engine temperature display on the scan tool for 2 to 5 minutes.

Is the engine temperature more than the specified value?

215°F

102°C

Go to Engine Overheating in Engine Cooling

Go to step 21

Replace the high engine temperature switch. Refer to Engine Protection System Temperature Switch Replacement

Is the action complete?

Go to step 22

Replace the low coolant switch. Refer to Engine Protection System manufacturer Hewitt Industries.

Is the action complete?

Go to step 22

Replace the engine protection system module. Refer to Engine Protection System manufacturer Hewitt Industries.

Is the action complete?

Go to step 22

Repair the short to ground on the oil pressure switch circuit. Refer to Wiring Repairs in Wiring Systems.

Go to step 22

Repair the short to ground on the high engine temperature switch circuit. Refer to Wiring Repairs in Wiring Systems.

Go to step 22

Start and idle the engine at normal operating temperature.
Operatre the vehicle within the conditions for triggering the engine protection system to shutdown the engine.
Monitor the following status lamps:

•	Low coolant level

•	Low oil pressure

•	High engine temperature

Are any of the status lamps on?

Go to step 5

System OK