Ford Mustang (1999-2004) Service Manual: Pinpoint Tests

CAUTION: Before removing and installing the GEM or its connectors, disconnect the battery. Failure to follow this caution will result in the GEM storing many erroneous DTCs and it may exhibit erratic operation after installation.

CAUTION: Be careful when probing the central junction box (CJB), battery junction box (BJB) or any connectors. Damage will result to the connector receptacle if the probe being used is too large.

CAUTION: Electronic modules are sensitive to static electrical charges. If exposed to these charges, damage may result.

NOTE: If continuous DTCs are recorded and the symptom is not present when carrying out the pinpoint tests, an intermittent concern may be the cause. Always check for loose connections and corroded terminals.

NOTE: Complete the entire pinpoint test related to the symptom before installing a new GEM.

PINPOINT TEST A: NO COMMUNICATION WITH THE GENERIC ELECTRONIC MODULE (GEM)

Test Step Result / Action to Take
CAUTION: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
A1 CHECK THE GENERIC ELECTRONIC MODULE (GEM) POWER SUPPLY Yes

GO to A2 .

No

REPAIR the circuit(s) in question. TEST the system for normal operation.
  • Key in OFF position.
  • Disconnect: Generic Electronic Module (GEM) C201a.
  • Disconnect: GEM C201b.
  • Key in ON position.
  • Using the following table. measure the voltage between the GEM, harness side and ground

  • Are the voltages greater than 10 volts?
A2 CHECK THE GEM GROUND CIRCUIT 397 (BK/WH) FOR OPEN Yes

GO to A3 .

No

REPAIR the cirucit(s) in question. TEST the system for normal operation.
  • Key in OFF position.
  • Measure the resistance between the GEM C201b pin 4, circuit 397 (BK/WH), harness side and ground.

  • Is the resistance less than 5 ohms?
A3 CHECK CIRCUIT 397 (BK/WH) FOR SHORT TO POWER Yes

REPAIR the circuit. TEST the system for normal operation.

No

REFER to Section
  • Measure the voltage between the GEM C201b pin 4, circuit 397 (BK/WH), harness side and ground.

  • Is any voltage present?

PINPOINT TEST B: WINDSHIELD WIPERS DO NOT OPERATE / OPERATE CORRECTLY

Test Step Result / Action to Take
B1 DETERMINE IF GEM IS RECEIVING CORRECT IGNITION SWITCH STATUS Yes

GO to B2 .

No

REFER to Section
  • Key in OFF position.
  • Connect the diagnostic tool.
  • NOTE: If the vehicle is equipped with a manual transmission, depress the clutch while turning the ignition switch to START.
  • Monitor the GEM PIDs IGN_S, IGN_R IGN_A, and IGN_KEY while turning the ignition switch through the START, RUN, OFF and ACC positions.
  • Do the GEM PID values agree with the ignition switch positions?
B2 DETERMINE IF GEM IS RECEIVING CORRECT WIPER SWITCH STATUS FROM MULTIFUNCTION SWITCH Yes

GO to B3 .

No

GO to B6
  • Key in ON position.
  • Monitor PID WPMODE, while moving through all wiper control positions on the multifunction switch.
  • Do the GEM PID values agree with switch positions?
B3 TEST GEM CONTROL OF WIPER ON/OFF RELAY Yes

GO to B4

No

GO to B10
  • Trigger the GEM active command WIPER RLY ON and OFF.
  • Do the wipers turn ON and OFF?
B4 TEST THE GEM CONTROL OF WIPER HIGH/LOW RELAY Yes

GO to B5 .

No

GO to B16 .
  • Trigger the GEM active command WIPER RLY to ON.
  • Trigger the GEM active command SPEED RLY ON and OFF.
  • Does wiper speed change on activation and deactivation of SPEED RLY command?
B5 DETERMINE IF GEM IS RECEIVING CORRECT WIPER POSITION STATUS Yes

INSTALL a new GEM. For additional information, REFER to Section.

CLEAR the DTCs. REPEAT the self-test.

No

GO to B27 .
  • Monitor GEM PID WPPRKSW while turning the wipers ON using the multifunction switch.
  • Do the PID values agree with the wiper position?
B6 TEST THE MULTIFUNCTION SWITCH FOR NORMAL OPERATION Yes

GO to B7 .

No

INSTALL a new multifunction switch; REFER to Section . REPEAT the selftest.

CLEAR the DTCs
  • Disconnect: Multifunction Switch C202a.
  • Check the multifunction switch. Refer to Wiring Diagrams, Cell 149, Component Testing.
  • Is the multifunction switch OK?
B7 CHECK CIRCUITS 682 (DB), 684 (PK/YE), AND 680 (LB/OG) FOR SHORT TO BATTERY BETWEEN THE GEM AND THE MULTIFUNCTION SWITCH Yes

REPAIR the circuit(s) in question. REPEAT the selftest.

CLEAR the DTCs.

No

GO to B8 .
  • Disconnect: GEM C201e.
  • Key in ON position.
  • Using the following table, measure the voltage between the GEM C201e Pins, harness side and ground.

  • Are the voltages greater than 10 volts?
B8 CHECK CIRCUITS 682 (DB), 684 (PK/YE), AND 680 (LB/OG) FOR SHORT TO GROUND BETWEEN THE GEM AND THE MULTIFUNCTION SWITCH Yes

REPAIR the circuit(s) in question. REPEAT the selftest.

CLEAR the DTCs.

No

GO to B9 .
  • Key in OFF position.
  • Using the following table, measure the resistance between the GEM C201e Pins, harness side and ground.

  • Are the resistances greater than 10,000 ohms?
B9 CHECK CIRCUITS 682 (DB), 684 (PK/YE), AND 680 (LB/OG) FOR AN OPEN CONDITION BETWEEN GEM AND MULTIFUNCTION SWITCH Yes

INSTALL a new GEM. For additional information, REFER to Section.

REPEAT the self-test.

CLEAR the DTCs.

No

REPAIR circuit(s) in question.

REPEAT the self-test.

CLEAR the DTCs.
  • Using the following table, measure the resistance between the GEM C201e Pins, harness side and multifunction switch C202a Pins, harness side.

  • Are the resistances less than 5 ohms?
B10 CHECK CIRCUITS 65 (DG) FOR OPEN CIRCUIT CONDITION BETWEEN BJB AND CJB Yes

GO to B11 .

No

REPAIR circuit(s) in question.

REPEAT the self-test.

CLEAR the DTCs.
NOTE: Verify voltage at CJB F26 (30A) before carrying out this test.
  • Disconnect: Wiper On/Off Relay.
  • Measure the voltage between BJB ON and OFF wiper relay Pin 5, Circuit 65 (DG), harness side and ground; and between BJB wiper ON/OFF relay Pin 2, Circuit 65 (DG), harness side and ground

  • Are the voltages greater than 10 volts?
B11 ISOLATE PROBLEM BETWEEN GEM AND BJB Yes

GO to B12 .

No

GO to B22 .
  • Key in OFF position.
  • Connect a fused jumper wire (30A) between wiper ON/OFF relay Pin 3 and Pin 5, harness side.

  • Key in ON position.
  • Did the wiper motor activate?
B12 CARRY OUT THE WIPER ON/OFF RELAY COMPONENT TEST Yes

GO to B13 .

No

INSTALL a new wiper ON/OFF relay. REPEAT the self-test. CLEAR the DTCs
  • Check the wiper ON and OFF relay; refer to Wiring Diagrams, Cell 149, Component Testing.
  • Is the ON/OFF wiper relay OK?
B13 CHECK CIRCUIT 646 (YE/WH) FOR SHORT TO BATTERY BETWEEN GEM AND BJB Yes

REPAIR Circuit 646 (YE/WH). REPEAT the selftest.

CLEAR the DTCs.

No

GO to B14 .
  • Disconnect: Wiper On/Off Relay.
  • Disconnect: GEM C201d.
  • Measure the voltage between GEM C201d 3 Pin 12, Circuit 646 (YE/WH), harness side and ground.

  • Is the voltage greater than 10 volts?
B14 CHECK CIRCUIT 646 (YE/WH) FOR SHORT TO GROUND BETWEEN GEM AND BJB Yes

GO to B15 .

No

REPAIR Circuit 646 (YE/WH). REPEAT the selftest.

CLEAR the DTCs.
  • Measure the resistance between GEM C201d Pin 12, Circuit 646 (YE/WH), harness side and ground

  • Is the resistance greater than 10,000 ohms?
B15 CHECK CIRCUIT 646 (YE/WH) FOR OPEN BETWEEN GEM AND BJB Yes

INSTALL a new GEM. For additional information REFER to Section. REPEAT the self-test. CLEAR the DTCs.

No

REPAIR Circuit 646 (YE/WH). REPEAT the selftest.

CLEAR the DTCs.
  • Measure the resistance between GEM C201d Pin 12, Circuit 646 (YE/WH), harness side and BJB wiper ON/OFF relay Pin 1, Circuit 646 (YE/WH), harness side.

  • Is the resistance less than 5 ohms?
B16 CHECK CIRCUITS 65 (DG) AND 61 (YE/RD) FOR OPEN CONDITION BETWEEN BJB AND CJB Yes

GO to B17 .

No

REPAIR circuit in question.

REPEAT the self-test.

CLEAR the DTCs.
  • Disconnect: Wiper HIGH/LOW Relay.
  • Trigger the GEM active command WIPER RLY to ON.
  • Measure the voltages between BJB wiper HIGH/LOW relay Pin 86, Circuit 65 (DG), harness side and ground; and between BJB wiper HIGH/LOW relay Pin 30, Circuit 61 (YE/RD), harness side and ground.

  • Are the voltages greater than 10 volts?
B17 ISOLATE THE PROBLEM BETWEEN THE GEM AND THE BJB Yes

GO to B18 .

No

GO to B26 .
  • Trigger the GEM active command WIPER RLY to ON.
  • Connect a fused jumper wire (30A) between wiper HIGH/LOW relay Pin 30, Circuit 61 (YE/RD), harness side and Pin 87, Circuit 58 (WH), harness side.

  • Did the wiper motor speed increase with the jumper installed and slow down with the jumper removed?
B18 CARRY OUT COMPONENT TEST ON WIPER HIGH/LOW RELAY Yes

GO to B19 .

No

INSTALL a new wiper HIGH/LOW relay. REPEAT the self-test. CLEAR the DTCs.
  • Check the wiper HIGH/LOW relay; refer to Wiring Diagrams, Cell 149, Component Testing.
  • Is the wiper HIGH/LOW relay OK?
B19 CHECK CIRCUIT 647 (GY/LB) FOR SHORT TO BATTERY BETWEEN GEM AND BJB Yes

REPAIR Circuit 647 (GY/LB).

REPEAT the self-test.

CLEAR the DTCs.

No

GO to B20 .
  • Disconnect: GEM C201d.
  • Measure voltage between GEM C201d Pin 5, Circuit 647 (GY/LB), harness side and ground.

  • Is the voltage greater than 10 volts?
B20 CHECK CIRCUIT 647 (GY/LB) FOR SHORT TO GROUND BETWEEN GEM AND BJB Yes

GO to B21 .

No

REPAIR Circuit 647 (GY/LB).

REPEAT the self-test.

CLEAR the DTCs.
  • Measure the resistance between GEM C201d Pin 5, Circuit 647 (GY/LB), harness side and ground.

  • Is the resistance greater than 10,000 ohms?
B21 CHECK CIRCUIT 647 (GY/LB) FOR OPEN CONDITION BETWEEN GEM AND BJB Yes

INSTALL a new GEM.

REFER to Section.

REPEAT the self-test.

CLEAR the DTCs.

No

REPAIR Circuit 647 (GY/LB).

REPEAT the self-test.

CLEAR the DTCs.
  • Measure the resistance between GEM C201d Pin 5, Circuit 647 (GY/LB), harness side and wiper HIGH/LOW relay Pin 85, Circuit 647 (GY/LB), harness side.

  • Is the resistance less than 5 ohms?
B22 CHECK CIRCUIT 61 (YE/RD) FOR OPEN CIRCUIT CONDITION BETWEEN WIPER ON/OFF AND HIGH/LOW RELAYS Yes

GO to B23 .

No

REPAIR Circuit 61 (YE/RD).

REPEAT the self-test.

CLEAR the DTCs.
  • Disconnect: Wiper HIGH/LOW Relay.
  • Disconnect: Wiper ON/OFF Relay.
  • Measure the resistance between wiper ON/OFF relay Pin 3, Circuit 61 (YE/RD), harness side and wiper HIGH/LOW relay Pin 30, Circuit 61 (YE/RD), harness side

  • Is the resistance less than 5 ohms?
B23 CARRY OUT THE WIPER HIGH/LOW RELAY COMPONENT TEST Yes

GO to B24 .

No

INSTALL a new wiper HIGH/LOW relay. REPEAT the self-test. CLEAR the DTCs.
  • Check the wiper HIGH/LOW relay; refer to Wiring Diagrams, Cell 149, Component Testing.
  • Is the wiper HIGH/LOW relay OK?
B24 CHECK CIRCUIT 56 (DB/OG) FOR AN OPEN CIRCUIT BETWEEN THE WIPER HIGH/LOW RELAY AND THE WIPER MOTOR Yes

GO to B25 .

No

REPAIR Circuit 56 (DB/OG).

REPEAT the self-test.

CLEAR the DTCs.
  • Disconnect: Wiper Motor C125.
  • Measure the resistance between wiper HIGH/LOW relay Pin 87A, Circuit 56 (DB/OG), harness side and wiper motor C125 Pin 4, Circuit 56 (DB/OG), harness side.

  • Is the resistance less than 5 ohms?
B25 CHECK CIRCUIT 1205 (BK) FOR OPEN CIRCUIT CONDITION BETWEEN WIPER MOTOR AND GROUND Yes

CARRY OUT the windshield wiper motor component test.

REFER to Component Test.

If the component fails, INSTALL a new wiper motor; REFER to Motor-Windshield Wiper . REPEAT the self-test.

CLEAR the DTCs.

No

REPAIR Circuit 1205 (BK).

REPEAT the self-test.

CLEAR the DTCs.
  • Measure the resistance between wiper motor C125 Pin 3, Circuit 1205 (BK), harness side and ground

  • Is the resistance less than 5 ohms?
B26 CHECK CIRCUIT 58 (WH) FOR AN OPEN CIRCUIT BETWEEN THE WIPER HIGH/LOW RELAY AND THE WIPER MOTOR Yes

CARRY OUT the windshield wiper motor component test.

REFER to Component Test.

If the component fails, INSTALL a new wiper motor; REFER to Motor-Windshield Wiper . REPEAT the self-test.

CLEAR the DTCs.

No

REPAIR Circuit 58 (WH).

REPEAT the self-test.

CLEAR the DTCs.
  • Disconnect: Wiper Motor C125.
  • Measure the resistance between wiper motor C125 Pin 5, Circuit 58 (WH), harness side and wiper HIGH/LOW relay Pin 87, Circuit 58 (WH), harness side.c

  • Is the resistance less than 5 ohms?
B27 CHECK CIRCUIT 28 (BK/PK) FOR OPEN CIRCUIT CONDITION BETWEEN THE WIPER HIGH/LOW RELAY AND THE WIPER MOTOR Yes

INSTALL a new wiper motor; REFER to Motor-Windshield Wiper . REPEAT the self-test.

CLEAR the DTCs.

No

REPAIR Circuit 28 (BK/PK).

REPEAT the self-test.

CLEAR the DTCs.
  • Disconnect: Wiper Motor C125.
  • Disconnect: GEM C201d.
  • Measure the resistance between wiper motor C125 Pin 1, Circuit 28 (BK/PK), harness side and GEM C201d Pin 1, Circuit 58 (WH), harness side.

  • Is the resistance less than 5 ohms?

PINPOINT TEST C: WINDSHIELD WASHERS DO NOT OPERATE / OPERATE CORRECTLY

Test Step Result / Action to Take
C1 DETERMINE IF GEM IS RECEIVING CORRECT IGNITION SWITCH STATUS Yes

GO to C2 .

No

REFER to Section
  • Key in OFF position.
  • Connect the diagnostic tool.
  • NOTE: If the vehicle is equipped with a manual transmission, depress the clutch while turning the ignition switch to START.
  • Monitor the GEM PIDs IGN_S, IGN_R IGN_A, and IGN_KEY while turning the ignition switch through the START, RUN, OFF and ACC positions.
  • Do the GEM PID values agree with the ignition switch positions?
C2 DETERMINE IF GEM IS RECEIVING CORRECT WIPER SWITCH STATUS FROM MULTIFUNCTION SWITCH Yes

GO to C3 .

No

GO to Pinpoint Test B .
  • Key in ON position.
  • Monitor GEM PID WPMODE while activating all wiper control positions on the multifunction switch.
  • Does the GEM PID values agree with switch positions?
C3 CHECK GEM CONTROL OF THE WASHER ON/OFF RELAY Yes

INSTALL a new GEM; REFER to Section . REPEAT the self-test. CLEAR the DTCs.

No

GO to C4 .
  • Trigger GEM active command WASH RLY ON and OFF.
  • Do washers turn ON and OFF?
C4 CHECK CIRCUIT 65 (DG) FOR OPEN CIRCUIT BETWEEN CJB AND WASHER ON/OFF RELAY Yes

GO to C5 .

No

REPAIR the circuit in question. REPEAT the self-test. CLEAR the DTCs.
NOTE: Verify voltage at CJB F26 (30A) before carrying out this test.
  • Disconnect: Washer ON/OFF Relay.
  • Measure the voltage between washer ON/OFF relay Pin 2, Circuit 65 (DG), harness side and ground; and washer ON/OFF relay Pin 3, Circuit 65 (DG), harness side and ground

  • Are the voltages greater than 10 volts?
C5 ISOLATE THE PROBLEM BETWEEN GEM AND BJB Yes

GO to C6 .

No

GO to C10
  • Connect a fused jumper wire (30A) between washer ON/OFF relay Pin 3, Circuit 65 (DG), harness side and Pin 5, Circuit 941 (BK/WH), harness side

  • Did the washer motor activate?
C6 CARRY OUT WASHER ON/OFF RELAY COMPONENT TEST Yes

GO to C7 .

No

INSTALL a new wiper ON/OFF relay.

REPEAT the self-test.

CLEAR the DTCs.
  • Check the washer ON/OFF relay; refer to Wiring Diagrams, Cell 149, Component Testing.
  • Is the washer ON/OFF relay OK?
C7 CHECK CIRCUIT 686 (TN/RD) FOR SHORT TO BATTERY BETWEEN GEM AND BJB Yes

REPAIR Circuit 686 (TN/RD). REPEAT the self-test. CLEAR the DTCs.

No

GO to C8
  • Disconnect: GEM C201d.
  • Measure the voltage between GEM C201d Pin 6, Circuit 686 (TN/RD), harness side and ground.

  • Is the voltage greater than 10 volts?
C8 CHECK CIRCUIT 686 (TN/RD) FOR SHORT TO GROUND BETWEEN GEM AND BJB Yes

GO to C9 .

No

REPAIR Circuit 686 (TN/RD). REPEAT the self-test. CLEAR the DTCs.
  • Measure the resistance between GEM C201d Pin 6, Circuit 686 (TN/RD), harness side and ground.

  • Is the resistance greater than 10,000 ohms?
C9 CHECK CIRCUIT 686 (TN/RD) FOR AN OPEN CIRCUIT BETWEEN GEM AND WASHER ON/OFF RELAY Yes

INSTALL a new GEM; REFER to Section . REPEAT the self-test. CLEAR the DTCs.

No

REPAIR Circuit 686 (TN/RD). REPEAT the self-test. CLEAR the DTCs.
  • Measure the resistance between GEM C201d Pin 6, Circuit 686 (TN/RD), harness side and washer ON/OFF relay Pin 1, Circuit 686 (TN/RD), harness side.

  • Is the resistance less than 5 ohms?
C10 CHECK CIRCUIT 941 (BK/WH) FOR SHORT TO BATTERY BETWEEN BJB AND WASHER MOTOR Yes

REPAIR Circuit 941 (BK/WH). REPEAT the self-test. CLEAR the DTCs.

No

GO to C11 .
  • Disconnect: Washer Pump Motor C137.
  • Measure the voltage between washer pump C137 Pin 1, Circuit 941 (BK/WH), harness side and ground

  • Is the voltage greater than 10 volts?
C11 CHECK CIRCUIT 941 (BK/WH)FOR OPEN BETWEEN THE BJB AND THE WASHER MOTOR Yes

GO to C12 .

No

REPAIR Circuit 941 (BK/WH). REPEAT the self-test. CLEAR the DTCs.
  • Measure the resistance between washer pump C137 Pin 1, Circuit 941 (BK/WH), harness side and washer pump relay Pin 5, Circuit 941 (BK/WH), harness side.

  • Is the resistance less than 5 ohms?
C12 CHECK CIRCUIT 1205 (BK) FOR AN OPEN Yes

INSTALL a new washer motor.

REPEAT the self-test.

CLEAR the DTCs.

No

REPAIR Circuit 1205 (BK). REPEAT the self-test. CLEAR the DTCs.
  • Measure the resistance between washer pump C137 Pin 2, Circuit 1205 (BK), harness side and ground.

  • Is the resistance less than 5 ohms?
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