Electric Cooling Fan Diagnosis. Buick Riviera 1998

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1998 🢒 Riviera 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Electric Cooling Fan Diagnosis

Table 1:	Electric Cooling Fan Functional Check
Table 2:	Table #1 Electric Cooling Fan (Fans Run When They Should Be Off)
Table 3:	Table #2 Electric Cooling Fan (Both Fans Inop or LH Fan on High and RH Fan Inop, in Low Speed)
Table 4:	Electric Cooling Fan (LH, RH, or Both Fans Inoperative in High Speed)
Table 5:	Table #4 Electric Cooling Fan (A/C Pressure Sensor Test)

Refer to Engine Controls Schematics for a wiring diagram.

Circuit Description

Power for the fan motors is supplied through the Cooling Fan fuse in the under Maxi fuse block. The cooling fan relays are energized when current flows from the Cooling Fan fuse in the IP fuse block through the relay coils to ground through the PCM. The cooling fan 1 control circuit is grounded for low speed fan operation. The cooling fan 1 and cooling fan 2 control circuits are grounded for high speed operation.

During low speed fan operation the PCM supplies a ground path for the low speed cooling fan relay #1. This closes the low speed relay contacts, allowing current to flow from the battery junction block through the relay contacts to the primary cooling fan. During low speed operation, the ground path for the primary cooling fan is through the series/parallel cooling fan relay and secondary cooling fan motor. The result is a series circuit with both fans running at low speed.

During high speed cooling fan operation the PCM supplies a ground path for the low speed cooling fan relay through the cooling fan 1 control circuit. The PCM also supplies a ground path for the high speed cooling fan relay #3 and the series/parallel cooling fan relay #2 through the cooling fan 2 control circuit. This closes all three fan relays. During high speed operation, both the primary and the secondary cooling fans are supplied current from the battery junction block and each fan has its own ground path.

Diagnostic Aids

Check for the following conditions:

•	Poor connection at the PCM, cooling fan relays, or cooling fan motors.

Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

•	Damaged harness.

Inspect the wiring harness for damage.

Electric Cooling Fan Functional Check

Step	Action	Value(s)	Yes	No
1	Was the On-Board Diagnostic (OBD) System Check performed?		Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Are any DTCs set?		Go to the applicable DTC table	Go to Step 3
3	Important: The engine coolant temperature must be below the specified value for all of the fan diagnoses. Install a scan tool. Turn ON the ignition, leaving the engine and the A/C OFF. Are the cooling fans OFF?	100°C (212°F)	Go to Step 4	Go to Electric Cooling Fan Function Check - Fans Run When Should be Off
4	Using a scan tool, command the cooling fan relay #1 ON. Are both of the cooling fans ON, running at low speed?	--	Go to Step 5	Go to Electric Cooling Fan Function Check - Both Fans Inop or LH Fan High and RH Fan Inop
5	Using a scan tool, command the cooling fan relay #2 ON. Wait 6 seconds. Do both of the cooling fans switch to high speed?	--	Go to Step 6	Go to Electric Cooling Fan Function Check - LH, RH, or Both Fans Inop in High Speed
6	Using a scan tool, exit ouput controls. Turn ON the engine, leaving the A/C OFF. Are the cooling fans ON?	--	Go to Step 7	Go to Step 9
7	Observe the scan tool. Does the scan tool display Cooling Fan 1 Command ON?	--	Go to Step 8	Go to Step 12
8	Observe the scan tool. Does the scan tool display Cooling Fan 2 Command ON?	--	Go to Electric Cooling Fan Function Check - A/C Pressure Sensor Test	Go to Step 9
9	Important: Ambient temperature must be above 9°C (48°F). Turn ON the engine. Turn ON the A/C. Are the cooling fans ON?	--	Go to Step 10	Go to Step 11
10	Turn ON the engine, leaving the A/C OFF. Does the scan tool display A/C request as a YES?	--	Go to Powertrain Control Module Controlled Air Conditioning (A/C) Circuit Diagnosis .	Go to Step 11
11	Turn ON the engine. Turn ON the A/C. Does the scan tool display A/C request as a YES?	--	System OK. For intermittent conditions, go to Diagnostic Aids	Go to Powertrain Control Module Controlled Air Conditioning (A/C) Circuit Diagnosis .
12	Important: The new powertrain control module (PCM) must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete?	--	Go to Step 1	--

Table #1 Electric Cooling Fan (Fans Run When They Should Be Off)

Step	Action	Value(s)	Yes	No
1	Did you perform the On-Board Diagnostic (OBD) System Check?	--	Go to Step 2	Go to Cooling Fan Functional Check
2	Install a scan tool. The engine coolant temperature must be below the specified value for all of the fan diagnoses. Turn the ignition ON leaving the engine and A/C OFF. Are the Cooling fans ON?	100°C (212°F)	Go to Step 3	Go to Cooling Fan Functional Check
3	Does the scan tool display either the Cooling Fan 1 or Cooling Fan 1 and 2 Command ON?	--	Go to Step 4	Go to Step 5
4	Use a scan tool in order to command the cooling fan relay number 1 OFF. Are both of the cooling fans OFF?	--	Go to Cooling Fan Functional Check	Go to Step 5
5	Disconnect the cooling fan relay number 1. Are both of the cooling fans OFF?	--	Go to Step 7	Go to Step 6
6	Disconnect the cooling fan relay number 2. Are both of the cooling fans OFF?	--	Go to Step 8	Go to Step 9
7	Replace the cooling fan relay number 1. Refer to. Is the action complete?	--	Go to Cooling Fan Functional Check	--
8	Replace the cooling fan number 2. Refer to. Is the action complete?	--	Go to Cooling Fan Functional Check	--
9	Locate and repair the short to B+ in CKTs 532, 504, or 409. Refer to .Is the action complete?	--	Go to Cooling Fan Functional Check	--

Table #2 Electric Cooling Fan (Both Fans Inop or LH Fan on High and RH Fan Inop, in Low Speed)

Step

Action

Value(s)

Yes

Was the Cooling Fan Functional Check Performed?

Go to Step 2

Go to Cooling Fan Functional Check

Install a scan tool.
The engine coolant temperature must be below the specified value for all of the following fan diagnostics.
Turn ON the ignition, with the engine OFF.
Turn OFF the A/C.
Using a scan tool, command the number 1 cooling fan relay ON.

Do both cooling fans come ON?

100°C (212°F)

Go to Cooling Fan Functional Check

Go to Step 3

Is the left hand cooling fan ON in high speed with the right hand cooling fan OFF?

Go to Step 4

Go to Step 7

Remove the cooling fan relay number 2.
Turn ON the ignition, with the engine OFF.
Using a scan tool, command the number 1 cooling fan relay ON.

Is the left hand cooling fan ON with the right hand cooling fan OFF?

Go to Step 5

Go to Step 6

Locate and repair the short to ground in CKT 504. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

Go to Cooling Fan Functional Check

Replace the number 2 cooling fan relay.

Is the action complete?

Go to Cooling Fan Functional Check

Turn OFF the ignition.
Check the cooling fan fuse(60 amp).

Is the fuse OPEN.

Go to Step 8

Go to Step 10

Locate and correct the short circuit. Refer to Repair Procedures in Electrical Diagnosis.

•	Stalled LH or RH cooling fan motor

•	Shorted LH or RH cooling fan motor

•	Short to ground in CKT 532, CKT 409, or B+ feed to the cooling fan relays 1 and 3

•	Shorted LH cooling fan diode

Is the action complete?

Go to Step 9

Replace the OPEN cooling fan fuse.

Is the action complete?

Go to Cooling Fan Functional Check

Turn ON the ignition, with the engine OFF.
Turn OFF the A/C.
Using a scan tool, command the number 2 cooling fan relay ON.

Is the left hand cooling fan ON in high speed with the right hand cooling fan OFF?

Go to Step 13

Go to Step 11

Turn ON the ignition, with the engine OFF.
Turn OFF the A/C.
Using a scan tool, command the number 2 cooling fan relay ON and then wait 6 seconds.

Is the right hand cooling fan ON in high speed with the left hand cooling fan OFF?

Go to Step 19

Go to Step 12

Repair the open ground CKT 1350 at G103.

Is the action complete?

Go to Cooling Fan Functional Check

Disconnect the RH cooling fan motor electrical connector.
Probe terminal B with a test lamp connected to a ground.
Turn ON the ignition, with the engine OFF.
Turn OFF the A/C.
Using a scan tool, command the number 1 cooling fan relay ON.

Does the test lamp illuminate?

Go to Step 14

Go to Step 16

Probe terminal A with a test lamp connected to B+.

Does the test lamp illuminate?

Go to Step 15

Go to Step 18

Check for poor connections at the RH fan motor, if OK replace the RH cooling fan motor.

Is the action complete?

Go to Cooling Fan Functional Check

Check for an open in CKT 409 between the number 2 cooling fan relay and the RH cooling fan motor connector. Refer to Wiring Repairs in Wiring Systems.

Did you find and repair a problem?

Go to Cooling Fan Functional Check

Go to Step 17

Check the connections at the number 2 cooling fan relay, if OK replace the number 2 cooling fan relay.

Is the action complete?

Go to Cooling Fan Functional Check

Locate and repair the open in CKT 1350. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

Go to Cooling Fan Functional Check

Disconnect the LH cooling fan motor electrical connector.
Probe terminal B with a test lamp connected to a ground.
Turn ON the ignition, with the engine OFF.
Turn OFF the A/C.
Using a scan tool, command the number 1 cooling fan relay ON.

Does the test lamp illuminate?

Go to Step 20

Go to Step 22

Probe terminal A with a test lamp connected to B+.

Does the test lamp illuminate?

Go to Step 21

Go to Step 25

Check for poor connections at the LH fan motor, if OK replace the LH cooling fan motor.

Is the action complete?

Go to Cooling Fan Functional Check

Remove the cooling fan relay number 1.
Note the terminal identification on the bottom of the relay.
Install a fused jumper with the proper terminal ends between terminal 30 and 87 for relay number 1 in the underhood junction block.
Probe terminal B in the LH cooling fan motor connector with a test lamp connected to ground.

Does the test lamp illuminate?

Go to Step 23

Go to Step 24

Check the connections at the cooling fan relay number 1, if OK replace the cooling fan relay number 1.

Is the action complete?

Go to Cooling Fan Functional Check

Locate and repair the following circuit condition(s). Refer to Wiring Repairs in Wiring Systems.

•	An open in CKT 532 between the LH cooling fan connector terminal B and the cooling fan relay number 1

•	An open in the B+ feed to the cooling fan relay number 1

Is the action complete?

Go to Cooling Fan Functional Check

Remove the cooling fan relay number 2.
Note the terminal identification on the bottom of the relay.
Install a fused jumper with the proper terminal ends between terminal 30 and 87a for relay number 2 in the underhood junction block.
Probe terminal A in the LH cooling fan motor connector with a test lamp connected to B+.

Does the test lamp illuminate?

Go to Step 26

Go to Step 27

Check the connections at the cooling fan relay number 2, if OK replace the cooling fan relay number 2.

Is the action complete?

Go to Cooling Fan Functional Check

Connect a test lamp between B+ and terminal 87a in the Underhood Junction Block using the proper jumper.

Does the test lamp illuminate?

Go to Step 28

Go to Step 29

Locate and repair the following circuit condition. Refer to Repair Procedures in Electrical Diagnosis.

An open in CKT 504 between the LH cooling fan connector terminal A and the cooling fan relay number 2, terminal 30.

Is the action complete?

Go to Cooling Fan Functional Check

Locate and repair the following circuit condition. Refer to Wiring Repairs in Wiring Systems.

An open in CKT 409 between the cooling fan relay number 2 terminal 87a and the RH cooling fan motor connector terminal B.

Is the action complete?

Go to Cooling Fan Functional Check

Electric Cooling Fan (LH, RH, or Both Fans Inoperative in High Speed)

Step

Action

Value(s)

Yes

Was the electric cooling fan functional check performed/

Go to Step 2

Go to Cooling Fan Functional Check

Important: The engine coolant temperature must be below the specified value for all of the fan diagnoses.

Install a scan tool.
Turn ON the ignition, leaving the engine OFF and the A/C OFF.
Using the scan tool, command ON the cooling fan relay #1.

Do both cooling fans turn ON?

100°C (212°F)

Go to Step 3

Go to Cooling Fan Functional Check

Turn ON the ignition, leaving the engine OFF.
Using the scan tool, command ON the cooling fan relay #2.
Wait 6 seconds.

Are both cooling fans ON at high speed?

Go to Cooling Fan Functional Check

Go to Step 4

Determine if the left hand cooling fan is operating at high speed.

Is the right hand cooling fan inoperative?

Go to Step 5

Go to Step 12

Remove the cooling fan relay #3.
Using a J 35616-200 test light, check for voltage at terminal 87 in the underhood junction block.

Is the test light ON?

Go to Step 6

Go to Step 7

Check for an open in the B+ feed to cooling fan relay #3. Refer to Repair Procedures in Electrical Diagnosis.

Was a problem found and corrected?

Go to Cooling Fan Functional Check

Remove the cooling fan relay #3.
Note the terminal identification on the bottom of the relay.
Install a fused jumper with the proper terminal ends between terminal 30 and terminal 87 for cooling fan relay #3 in the underhood junction block.
Observe the right hand cooling fan.

Is the right hand cooling fan running at high speed?

Go to Step 8

Go to Step 11

Note the terminal identification on the bottom of the relay.
Install a J 35616-200 test light using the proper terminal ends between terminal 85 and terminal 86 for cooling fan relay #3 in the underhood junction block.
Turn ON the ignition, leaving the engine and the A/C OFF.
Using a scan tool, command ON the cooling fan relay #2.
Wait 6 seconds.

Is the test light ON?

Go to Step 9

Go to Step 10

Replace cooling fan relay #3. Refer to Electrical Center Identification Views .

Is the action complete?

Go to Cooling Fan Functional Check

Locate and repair the following circuit conditions:

•	The open in the cooling fan 2 high speed control circuit between the powertrain control module (PCM) and cooling fan relay #3, terminal 86.

•	The open in the B+ feed to cooling fan relay #3, terminal 86

Refer to Repair Procedures in Electrical Diagnosis.

Is the action complete?

Go to Cooling Fan Functional Check

Locate and repair the open in circuit 409 between the cooling fan relay #3 and the right hand cooling fan motor. Refer to Repair Procedures in Electrical Diagnosis

Is the action complete?

Go to Cooling Fan Functional Check

Determine if the right hand cooling fan is operating at high speed.

Is the left hand cooling fan inoperative?

Go to Step 13

Go to Cooling Fan Functional Check

Remove the cooling fan relay #32
Note the terminal identification on the bottom of the relay.
Install a fused jumper with the proper terminal ends between terminal 30 and terminal 87 for cooling fan relay #2 in the underhood junction block.
Turn ON the ignition, leaving the engine and the A/C OFF.
Using a scan tool, command ON cooling fan relay #1.

Is the left hand cooling fan running at high speed?

Go to Step 14

Go to Step 17

Note the terminal identification on the bottom of the relay.
Install a J 35616-200 test light using the proper terminal ends between terminal 85 and terminal 86 for cooling fan relay #2 in the underhood junction block.
Turn ON the ignition, leaving the engine and the A/C OFF.
Using a scan tool, command ON the cooling fan relay #2.
Wait 6 seconds.

Is the test light ON?

Go to Step 15

Go to Step 16

Replace cooling fan relay #2.

Is the action complete/

Go to Cooling Fan Functional Check

Locate and repair the following circuit conditions:

•	The open in the cooling fan 2 high speed control circuit between the powertrain control module (PCM) and cooling fan relay #2, terminal 85.

•	The open in the B+ feed to cooling fan relay #3, terminal 86

Refer to Repair Procedures in Electrical Diagnosis.

Is the action complete?

Go to Cooling Fan Functional Check

Locate and repair the open in circuit 1350 between the cooling fan relay #2, terminal 87, and G103. Refer to Repair Procedures in Electrical Diagnosis.

Is the action complete?

Go to Cooling Fan Functional Check

Table #4 Electric Cooling Fan (A/C Pressure Sensor Test)

Step	Action	Value(s)	Yes	No
1	Was the cooling fan functional check performed/	--	Go to Step 2	Go to Cooling Fan Functional Check
2	Install a scan tool. Turn ON the ignition, leaving the engine and the A/C OFF. View the A/C Pressure on the scan tool. Does the scan tool display voltage near the specified value?	1.5 V	Go to Step 11	Go to Step 3
3	Turn OFF the ignition. Disconnect the A/C refrigerant pressure sensor electrical connector. Turn ON the ignition. View the A/C Pressure on the scan tool. Does the scan tool display voltage near the specified value/	0 V	Go to Step 4	Go to Step 7
4	Probe the A/C refrigerant pressure sensor ground with a J 35616-200 test lamp connected to B+. Is the test lamp ON?	--	Go to Step 5	Go to Step 9
5	Probe the A/C refrigerant pressure sensor 5 V reference B circuit with a J 39200 digital multimeter (DMM). Does the DMM display voltage near the specified value?	5 V	Go to Step 6	Go to Step 10
6	Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement in Heating, Ventilation and Air Conditioning. Is the action complete?	--	Go to Cooling Fan Functional Check	--
7	Probe the A/C refrigerant pressure sensor signal circuit with a J 39200 DMM. Does the DMM display voltage near the specified value?	0 V	Go to Step 11	Go to Step 8
8	Locate and repair the short to voltage in the A/C refrigerant pressure sensor signal circuit. Refer to Repair Procedures in Electrical Diagnosis. Is the action complete?		Go to Cooling Fan Functional Check
9	Locate and repair the open or the short to voltage in the A/C refrigerant pressure sensor ground circuit. Refer to Repair Procedures in Electrical Diagnosis. Is the action complete?		Go to Cooling Fan Functional Check
10	Locate and repair the open or the short to voltage in the A/C refrigerant pressure sensor 5 V reference B circuit. Refer to Repair Procedures in Electrical Diagnosis. Is the action complete?		Go to Cooling Fan Functional Check
11	Important: The new powertrain control module (PCM) must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete?		Go to Cooling Fan Functional Check