Ford Mustang (1999-2004) Service Manual: Seats (Diagnosis and Testing)

Refer to Wiring Diagrams Cell 120 , Power Seats for schematic and connector information.

Refer to Wiring Diagrams Cell 122 , Power Lumbar Seats for schematic and connector information.

Special Tool(s)

73 III Automotive Meter 105-R0057

Inspection and Verification

1. Verify the customer concern by operating the system.

2. Visually inspect for obvious signs of mechanical or electrical damage.

Visual Inspection Chart

Mechanical	Electrical
Front seat track. Seat at limit(s) of travel	Battery junction box (BJB) Fuse Power Seat (25A). Loose, corroded or damaged connectors. Seat regulator control switch. Lumbar seat control switch. Lumbar motor. Bolster and lumbar control switches (cobra)

3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

4. If the concern is not visually evident, verify the symptom. GO to Symptom Chart .

Symptom Chart

Refer to the Wiring Diagram manual for the connector numbers cited in the pinpoint tests.

Condition	Possible Sources	Action
The power seat is inoperative	BJB Fuse Power Seat (25A) Seat regulator control switch. Circuitry. Seat track.	Go To Pinpoint Test A .
The power seat does not move vertically - front	Seat regulator control switch. Seat track. Circuitry.	Go To Pinpoint Test B .
The power seat does not move vertically - rear	Seat regulator control switch. Seat track. Circuitry.	Go To Pinpoint Test C .
The power seat does not move horizontally	Seat regulator control switch. Seat track. Circuitry.	Go To Pinpoint Test D .
The power lumbar is inoperative	Lumbar motor. Lumbar seat control switch. Circuitry	Go To Pinpoint Test E .
The power bolster/lumbar is inoperative (Cobra only)	Bolster/lumbar pump and solenoid module. Bolster/lumbar seat control switches. Circuitry.	Go To Pinpoint Test F .

Pinpoint Tests

PINPOINT TEST A: THE POWER SEAT IS INOPERATIVE

Test Step	Result / Action to Take
A1 CHECK CIRCUIT 566 (DG)	Yes GO to A2 . No REPAIR the circuit. TEST the system for normal operation.
Disconnect: Seat Regulator Control Switch C360. Measure the voltage between seat regulator control switch C360-2, Circuit 566 (DG), harness side and ground. Is the voltage greater than 10 volts?
A2 CHECK CIRCUIT 1205 (BK) FOR AN OPEN	Yes GO to A3 . No REPAIR the circuit. TEST the system for normal operation
Measure the resistance between seat regulator control switch C360-4, Circuit 1205 (BK), harness side and ground. Is the resistance less than 5 ohms?
A3 CHECK THE SEAT REGULATOR CONTROL SWITCH	Yes CHECK for obstructed or binding seat track. If no obstructions are found, INSTALL a new seat track. REFER to Seat Track . TEST the system for normal operation. No INSTALL a new seat regulator control switch. REFER to Switch-Seat Regulator Control . TEST the system for normal operation.
Carry out the seat regulator control switch component test. Refer to Wiring Diagrams. Did the seat regulator control switch pass?

PINPOINT TEST B: THE POWER SEAT DOES NOT MOVE VERTICALLY - FRONT

Test Step

Result / Action to Take

B1 CHECK THE MOTOR SUPPLY CIRCUITS

Yes

GO to B3 .

GO to B2 .

Disconnect: Front Height Motor C382.
NOTE: Make sure all connectors are connected on the seat.
Measure the resistance between front height motor C382, Circuit 979 (RD/LB), harness side and ground and between front height motor C382, Circuit 990 (YE/LB), harness side and ground.

Are the resistances less than 5 ohms?

B2 CHECK CIRCUIT 979 (RD/LB) AND 990 (YE/LB) FOR AN OPEN

Yes

INSTALL a new seat regulator control switch.

REFER to Switch- Seat Regulator Control . TEST the system for normal operation.

REPAIR the circuit.

TEST the system for normal operation.

Disconnect: Seat Regulator Control Switch C360.
Measure the resistance between front height motor C382, Circuit 979 (RD/LB), harness side and seat regulator control switch C360-7, Circuit 979 (RD/LB), harness side; then between front height motor C382, Circuit 990 (YE/LB), harness side and seat regulator control switch C360-5, Circuit 990 (YE/LB), harness side.

Is the resistance less than 5 ohms?

B3 CHECK CIRCUIT 979 (RD/LB) AND 990 (YE/LB) FOR A SHORT TO GROUND

Yes

GO to B4 .

REPAIR the circuit.

TEST the system for normal operation.

Measure the resistance between front height motor C382, Circuit 979 (RD/LB), harness side and ground and between front height motor C382, Circuit 990 (YE/LB), harness side and ground.

Are the resistances greater than 10,000 ohms?

B4 CHECK THE UP POSITION INPUT

Yes

GO to B5 .

INSTALL a new seat regulator control switch.

REFER to Switch- Seat Regulator Control . TEST the system for normal operation.

Connect: Seat Regulator Control Switch C360.
Measure the voltage between front height motor C382, Circuit 979 (RD/LB), harness side and ground.

Actuate the seat regulator control switch to the front UP position.
Is the voltage greater than 10 volts?

B5 CHECK THE DOWN POSITION INPUT

Yes

INSTALL a new seat track. REFER to Seat Track .

TEST the system for normal operation.

INSTALL a new seat regulator control switch.

REFER to Switch- Seat Regulator Control . TEST the system for normal operation.

Measure the voltage between front height motor C382, Circuit 990 (YE/LB), harness side and ground.

Actuate the seat regulator control switch to the front DOWN position.
Is the voltage greater than 10 volts?

PINPOINT TEST C: THE POWER SEAT DOES NOT MOVE VERTICALLY - REAR

Test Step

Result / Action to Take

C1 CHECK THE MOTOR SUPPLY CIRCUITS

Yes

GO to C3 .

GO to C2 .

Disconnect: Rear Height Motor C363.
NOTE: Make sure all connectors are connected on the seat.
Measure the resistance between rear height motor C363, Circuit 983 (RD/LG), harness side and ground and between rear height motor C363, Circuit 982 (YE/LG), harness side and ground.

Are the resistances less than 5 ohms?

C2 CHECK CIRCUIT 983 (RD/LG) AND 982 (YE/LG) FOR AN OPEN

Yes

INSTALL a new seat regulator control switch.

REFER to Switch- Seat Regulator Control . TEST the system for normal operation.

REPAIR the circuit.

TEST the system for normal operation.

Disconnect: Seat Regulator Control Switch C360.
Measure the resistance between rear height motor C363, Circuit 983 (RD/LG), harness side and seat regulator control switch C360-1, Circuit 983 (RD/LG), harness side; then between rear height motor C363, Circuit 982 (YE/LG), harness side and seat regulator control switch C360-6, Circuit 982 (YE/LG), harness side.

Is the resistance less than 5 ohms?

C3 CHECK CIRCUIT 983 (RD/LG) AND 982 (YE/LG) FOR A SHORT TO GROUND

Yes

GO to C4 .

REPAIR the circuit.

TEST the system for normal operation.

Measure the resistance between rear height motor C363, Circuit 983 (RD/LG), harness side and ground; and between rear height motor C363, Circuit 982 (YE/LG), harness side and ground.

Are the resistances greater than 10,000 ohms?

C4 CHECK THE UP POSITION INPUT

Yes

GO to C5 .

INSTALL a new seat regulator control switch.

REFER to Switch- Seat Regulator Control . TEST the system for normal operation.

Connect: Seat Regulator Control Switch C360.
Measure the voltage between rear height motor C363, Circuit 983 (RD/LG), harness side and ground.

Actuate the seat regulator control switch to the rear UP position.
Is the voltage greater than 10 volts?

C5 CHECK THE DOWN POSITION INPUT

Yes

INSTALL a new seat track. REFER to Seat Track .

TEST the system for normal operation.

INSTALL a new seat regulator control switch.

REFER to Switch- Seat Regulator Control . TEST the system for normal operation.

Measure the voltage between rear height motor C363, Circuit 982 (YE/LG), harness side and ground.

Actuate the seat regulator control switch to the rear DOWN position.
Is the voltage greater than 10 volts?

PINPOINT TEST D: THE POWER SEAT DOES NOT MOVE HORIZONTALLY

Test Step

Result / Action to Take

D1 CHECK THE MOTOR SUPPLY CIRCUITS

Yes

GO to D3 .

GO to D2

Disconnect: Horizontal Motor C362.
NOTE: Make sure all connectors are connected on the seat.
Measure the resistance between horizontal motor C362, Circuit 981 (RD/WH), harness side and ground; and between horizontal motor C362, Circuit 980 (YE/WH), harness side and ground

Are the resistances less than 5 ohms?

D2 CHECK CIRCUIT 981 (RD/WH) AND 980 (YE/WH) FOR AN OPEN

Yes

INSTALL a new seat regulator control switch.

REFER to Switch- Seat Regulator Control . TEST the system for normal operation.

REPAIR the circuit.

TEST the system for normal operation.

Disconnect: Seat Regulator Control Switch C360.
Measure the resistance between horizontal motor C362, Circuit 981 (RD/WH), harness side and seat regulator control switch C360-3, Circuit 981 (RD/WH), harness side; then between horizontal motor C362, Circuit 980 (YE/WH), harness side and seat regulator control switch C360-8, Circuit 980 (YE/WH), harness side.

Is the resistance less than 5 ohms?

D3 CHECK CIRCUIT 981 (RD/WH) AND 980 (YE/WH) FOR A SHORT TO GROUND

Yes

GO to D4 .

REPAIR the circuit.

TEST the system for normal operation.

Measure the resistance between horizontal motor C362, Circuit 981 (RD/WH), harness side and ground; and between horizontal motor C362, Circuit 980 (YE/WH), harness side and ground.

Are the resistances greater than 10,000 ohms?

D4 CHECK THE REARWARD POSITION INPUT

Yes

GO to D5 .

INSTALL a new seat regulator control switch.

REFER to Switch- Seat Regulator Control . TEST the system for normal operation.

Connect: Seat Regulator Control Switch C360.
Measure the voltage between horizontal motor C362, Circuit 981 (RD/WH), harness side and ground.

Actuate the seat regulator control switch to the REARWARD position.
Is the voltage greater than 10 volts?

D5 CHECK THE FORWARD POSITION INPUT

Yes

INSTALL a new seat track. REFER to Seat Track .

TEST the system for normal operation.

INSTALL a new seat regulator control switch.

REFER to Switch- Seat Regulator Control . TEST the system for normal operation.

Measure the voltage between horizontal motor C362, Circuit 980 (YE/WH), harness side and ground.

Actuate the seat regulator control switch to the FORWARD position.
Is the voltage greater than 10 volts?

PINPOINT TEST E: THE POWER LUMBAR IS INOPERATIVE

Test Step	Result / Action to Take
E1 CHECK THE LUMBAR COMPRESSOR OPERATION	Yes GO to E6 . No GO to E2 .
Actuate the lumbar seat control switch to the inflate position. Did the lumbar compressor motor run?
E2 CHECK CIRCUIT 566 (DG)	Yes GO to E3 . No REPAIR the circuit. TEST the system for normal operation.
Disconnect: Lumbar Seat Control Switch C361. Measure the voltage between lumbar seat control switch C361, Circuit 566 (DG), harness side and ground. Is the voltage greater than 10 volts?
E3 CHECK CIRCUIT 1205 (BK) FOR AN OPEN	Yes GO to E4 . No REPAIR the circuit. TEST the system for normal operation.
Disconnect: Lumbar Motor C366. Measure the resistance between lumbar motor C366, Circuit 1205 (BK), harness side and ground. Is the resistance less than 5 ohms?
E4 CHECK THE POWER SUPPLY TO THE LUMBAR MOTOR	Yes INSTALL a new lumbar motor. REFER to Lumbar Motor . TEST the system for normal operation. No GO to E5 .
Connect: Lumbar Seat Control Switch C361. Measure the voltage between lumbar motor C366, Circuit 51 (BK/WH), harness side and ground. Actuate the lumbar seat control switch the inflate position. Is the voltage greater than 10 volts?
E5 CHECK CIRCUIT 51 (BK/WH) FOR AN OPEN	Yes INSTALL a new lumbar seat control switch. REFER to Lumbar Control Switch . TEST the system for normal operation. No REPAIR the circuit. TEST the system for normal operation.
Disconnect: Lumbar Seat Control Switch C361. Measure the resistance between lumbar seat control switch C361, Circuit 51 (BK/WH), harness side and lumbar motor C366, Circuit 51 (BK/WH), harness side. Is the resistance less than 5 ohms?
E6 CHECK THE LUMBAR ADJUSTING SYSTEM	Yes GO to E10 . No GO to E7 .
Actuate the lumbar seat control switch to the inflate position while observing the seat backrest lumbar adjusting pad. Did the seat backrest lumbar adjusting pad inflate?
E7 CHECK THE SEAT BACKREST LUMBAR ADJUSTING PAD	Yes INSTALL a new seat backrest lumbar adjusting pad. REFER to Lumbar Assembly . TEST the system for normal operation. No GO to E8 .
Visually inspect the seat backrest lumbar adjusting pad. Is the seat backrest lumbar adjusting pad damaged?
E8 CHECK AIR FLOW FROM LUMBAR COMPRESSOR	Yes GO to E9 . No INSTALL a new lumbar motor. REFER to Lumbar Motor . TEST the system for normal operation
Disconnect the seat backrest lumbar adjusting hose from the lumbar motor. Actuate the lumbar seat control switch to the inflate position while feeling for air at the motor connection. Is air felt at the lumbar motor hose connection?
E9 CHECK THE AIR FLOW FROM THE LUMBAR SEAT CONTROL SWITCH	Yes GO to E10 . No INSTALL a new seat backrest lumbar adjusting hose. TEST the system for normal operation.
Reconnect the hose to the lumbar motor. Disconnect the seat backrest lumbar adjusting hose at the lumbar seat control switch. Actuate the lumbar seat control switch to the inflate position. Is air felt at the seat backrest lumbar adjusting hose?
E10 CHECK THE SYSTEM FOR LEAKS	Yes The system is operating correctly. TEST the system for normal operation. No GO to E11 .
Reconnect the hose at the lumbar seat control switch. Disconnect the seat backrest lumbar adjusting hose at the seat backrest lumbar adjusting pad. Install an in-line pressure gauge on the hose. Actuate the lumbar seat control switch to the inflate position until the gauge reads 34.47 kPa (5 psi). The system should hold pressure for three hours. After three hours, is the pressure reading 32.41 kPa (4.7 psi) or more?
E11 CHECK THE SEAT BACKREST LUMBAR ADJUSTING PAD FOR LEAKS	Yes INSTALL a new lumbar seat control switch. REFER to Lumbar Control Switch . TEST the system for normal operation. No INSTALL a new seat backrest lumbar adjusting pad. REFER to Lumbar Assembly . TEST the system for normal operation.
Remove the in-line pressure gauge. Use a hand pump and inflate the seat backrest lumbar adjusting pad to 34.47 kPa (5 psi). The seat backrest lumbar adjusting pad should hold pressure for three hours. After three hours, is the pressure reading 32.41 kPa (4.7 psi) or more?

PINPOINT TEST F: THE POWER BOLSTER/LUMBAR IS INOPERATIVE - DRIVER

Test Step	Result / Action to Take
F1 CHECK THE BOLSTER/LUMBAR COMPRESSOR OPERATION	Yes GO to F5 . No GO to F2 .
Actuate the bolster/lumbar seat control switches. Does the bolster/lumbar compressor motor run?
F2 CHECK CIRCUIT (BK) FOR VOLTAGE	Yes GO to F3 . No REPAIR the circuit. TEST the system for normal operation.
Disconnect: Bolster/lumbar pump and solenoid module. Measure the voltage at bolster/lumbar pump and solenoid module pin 1 (BK), harness side and ground. Is the voltage greater than 10 volts?
F3 CHECK CIRCUIT (LG) FOR AN OPEN	Yes GO to F4 . No REPAIR the circuit. TEST the system for normal operation.
Measure the resistance between bolster/lumbar pump and solenoid module pin 2, (LG), harness side and ground. Is the resistance less than 5 ohms?
F4 CHECK THE BOLSTER/LUMBAR SEAT CONTROL SWITCHES	Yes INSTALL a new bolster/lumbar pump and solenoid module. REFER to Lumbar Motor . TEST the system for normal operation. No INSTALL a new bolster/lumbar seat control switch. REFER to Lumbar Control Switch . TEST the system for normal operation.
Carry out the bolster/lumbar seat control switch component test. Refer to Wiring Diagrams Cell 149 for schematic and connector information. Did the seat control switches pass?
F5 CHECK THE LUMBAR ADJUSTING SYSTEM	Yes GO to F9 . No For seat backrest lumbar, GO to F6 . For seat backrest bolster, GO to F10 . For seat cushion bolster, GO to F14
Actuate the bolster/lumbar seat control switches to the inflate position while observing the seat backrest lumbar adjusting pad, backrest bolster and cushion bolster. Did the seat bolsters/lumbar adjusting pads inflate?
F6 CHECK THE SEAT BACKREST LUMBAR ADJUSTING PAD	Yes INSTALL a new seat backrest lumbar adjusting pad. REFER to Lumbar Assembly . TEST the system for normal operation. No GO to F7
Visually inspect the seat backrest lumbar adjusting pad. Is the seat backrest lumbar adjusting pad damaged?
F7 CHECK AIR FLOW FROM LUMBAR COMPRESSOR	Yes GO to F8 . No INSTALL a new bolster/lumbar pump and solenoid module. REFER to Front Seat Cushion . TEST the system for normal operation
Disconnect the seat backrest lumbar adjusting hose from the connection at the seat pivot bolt. Actuate the lumbar seat control switch to the inflate position while feeling for air at the connection. Is air felt at the lumbar motor hose connection?
F8 CHECK THE SYSTEM FOR LEAKS	Yes The system is operating correctly. TEST the system for normal operation. No GO to F9 .
Reconnect the hose at the seat backrest lumbar pivot bolt. Disconnect the seat backrest lumbar adjusting hose at the seat backrest lumbar adjusting pad. Install an in-line pressure gauge on the hose. Actuate the lumbar seat control switch to the inflate position until the gauge reads 34.47 kPa (5 psi). The system should hold pressure for three hours. After three hours, is the pressure reading 32.41 kPa (4.7 psi) or more?
F9 CHECK THE SEAT BACKREST LUMBAR ADJUSTING PAD FOR LEAKS	Yes INSTALL a new bolster/lumbar pump and solenoid module. REFER to Lumbar Motor . TEST the system for normal operation. No INSTALL a new seat backrest lumbar adjusting pad. REFER to Lumbar Assembly . TEST the system for normal operation.
Remove the in-line pressure gauge. Use a hand pump and inflate the seat backrest lumbar adjusting pad to 34.47 kPa (5 psi). The seat backrest lumbar adjusting pad should hold pressure for three hours. After three hours, is the pressure reading 32.41 kPa (4.7 psi) or more?
F10 CHECK THE SEAT BACKREST BOLSTER ADJUSTING PADS	Yes INSTALL a new seat backrest bolster adjusting pad. REFER to Lumbar Assembly . TEST the system for normal operation. No GO to F11 .
Visually inspect the seat backrest bolster adjusting pad. Is the seat backrest bolster adjusting pad damaged?
F11 CHECK AIR FLOW FROM BOLSTER COMPRESSOR	Yes GO to F12 . No INSTALL a new bolster/lumbar pump and solenoid module. REFER to Lumbar Motor . TEST the system for normal operation.
Disconnect the seat backrest bolster adjusting hose from the connection at the seat pivot bolt. Actuate the bolster seat control switch to the inflate position while feeling for air at the connection. Is air felt at the lumbar motor hose connection?
F12 CHECK THE SYSTEM FOR LEAKS	Yes The system is operating correctly. TEST the system for normal operation. No GO to F13 .
Reconnect the hose at the seat backrest bolster pivot bolt. Disconnect the seat backrest bolster adjusting hose at the seat backrest bolster adjusting pad. Install an in-line pressure gauge on the hose. Actuate the bolster seat control switch to the inflate position until the gauge reads 34.47 kPa (5 psi). The system should hold pressure for three hours. After three hours, is the pressure reading 32.41 kPa (4.7 psi) or more?
F13 CHECK THE SEAT BACKREST BOLSTER ADJUSTING PAD FOR LEAKS	Yes INSTALL a new bolster/lumbar pump and solenoid module. REFER to Lumbar Motor . TEST the system for normal operation. No INSTALL a new seat backrest bolster adjusting pad. REFER to Lumbar Assembly . TEST the system for normal operation.
Remove the in-line pressure gauge. Use a hand pump and inflate the seat backrest bolster adjusting pad to 34.47 kPa (5 psi). The seat backrest bolster adjusting pad should hold pressure for three hours. After three hours, is the pressure reading 32.41 kPa (4.7 psi) or more?
F14 CHECK THE SEAT CUSHION BOLSTER ADJUSTING PADS	Yes INSTALL a new seat cushion bolster adjusting pad. REFER to Lumbar Assembly . TEST the system for normal operation. No GO to F15
Visually inspect the seat cushion bolster adjusting pad. Is the seat cushion bolster adjusting pad damaged?
F15 CHECK AIR FLOW FROM BOLSTER COMPRESSOR	Yes GO to F16 . No INSTALL a new bolster/lumbar pump and solenoid module. REFER to Lumbar Motor . TEST the system for normal operation.
Disconnect the seat cushion bolster adjusting hose from the connection at the seat pivot bolt. Actuate the bolster seat control switch to the inflate position while feeling for air at the connection. Is air felt at the bolster motor hose connection?
F16 CHECK THE SYSTEM FOR LEAKS	Yes The system is operating correctly. TEST the system for normal operation. No GO to F17 .
Reconnect the hose at the seat cushion bolster pivot bolt. Disconnect the seat cushion bolster adjusting hose at the seat cushion bolster adjusting pad. Install an in-line pressure gauge on the hose. Actuate the bolster seat control switch to the inflate position until the gauge reads 34.47 kPa (5 psi). The system should hold pressure for three hours. After three hours, is the pressure reading 32.41 kPa (4.7 psi) or more?
F17 CHECK THE SEAT CUSHION BOLSTER ADJUSTING PAD FOR LEAKS	Yes INSTALL a new bolster/lumbar pump and solenoid module. REFER to Lumbar Motor . TEST the system for normal operation. No INSTALL a new seat cushion bolster adjusting pad. REFER to Lumbar Assembly . TEST the system for normal operation.
Remove the in-line pressure gauge. Use a hand pump and inflate the seat cushion bolster adjusting pad to 34.47 kPa (5 psi). The seat cushion bolster adjusting pad should hold pressure for three hours. After three hours, is the pressure reading 32.41 kPa (4.7 psi) or more?

Seats (Description and Operation)

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Switch - Seat Regulator Control

Removal and Installation 1. Disconnect the battery. For additional information, refer to Section. 2. Remove the screws and position the seat regulator control switch aside. 3. Disconnect the elec ...

Other materials:

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Changing a fuse
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