Section 13-01: Instrument Cluster—Conventional
1994 Mustang Workshop Manual
DIAGNOSIS AND TESTING

Pinpoint Tests

  

PINPOINT TEST A: INSTRUMENT CLUSTER INOPERATIVE

 

A1 CHECK CIRCUIT 640 (R/Y)

Yes
SERVICE short to ground in Circuit 640 (R/Y). RESTORE system. RETEST system.

No
GO to A2.

 

A2 CHECK PRINTED CIRCUIT SUPPLY CIRCUITS

Yes
REPLACE instrument cluster printed circuit . RESTORE system. RETEST system.

No
SERVICE open in circuits as required. RESTORE system. RETEST system.

  

PINPOINT TEST B: FUEL LEVEL READS ERRONEOUSLY

 

B1 VERIFY POWER AT FUSE PANEL (LOAD SIDE)

  • Use voltmeter to verify system voltage at load side of warning indicator Fuse 15 (10A).
  • Is voltage present at load side of fuse
Yes
GO to B3.

No
GO to B2.

 

B2 VERIFY POWER AT FUSE PANEL (FEED SIDE)

  • Use voltmeter to verify system voltage at feed side of warning indicator Fuse 15 (10A).
  • Is voltage present at feed side of fuse?
Yes
REPLACE fuse. RESTORE vehicle.

No
SERVICE wiring to fuse panel. RETEST system.

 

B3 VERIFY POWER AT CLUSTER

  • Instrument cluster connectors installed.
  • Partially remove instrument cluster .
  • Check for voltage at instrument cluster connector and gauge terminal.
  • Use Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent.
  • Is voltage at instrument cluster connector and gauge terminal?
Yes
GO to B4.

No
SERVICE Circuit 640 (R/Y) for open circuit. RESTORE vehicle. RETEST system.

 

B4 VERIFY GROUND CIRCUIT AT CLUSTER

  • Use Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent to check continuity of instrument cluster and gauge ground circuits.
  • Is there continuity?
Yes
GO to B5.

No
SERVICE circuit 563 (O/Y) for open circuit. RESTORE vehicle. RETEST system.

 

B5 CHECK TEST BOX (LOW)

  • Turn ignition switch to OFF position.
  • Insert Rotunda Instrument Gauge System Tester 021-00055 or equivalent in sender circuit.
  • Disconnect rear lamp wiring connector under instrument panel and connect tester to cluster side of connector.
  • Set tester to 22 ohms.
  • Turn ignition switch to RUN position, wait 60 seconds and read fuel gauge.
  • Does fuel gauge read EMPTY?
Yes
GO to B8.

No
GO to B6.

 

B6 CHECK TEST BOX (RETEST)

  • Turn ignition switch to OFF position.
  • Turn ignition switch to RUN position.
  • Tap lightly on instrument cluster , wait 60 seconds and read fuel gauge .
  • Does fuel gauge read EMPTY?
Yes
GO to B8.

No
GO to B7.

 

B7 ANTI-SLOSH MODULE BYPASS TEST

  • Turn ignition switch to OFF position.
  • Remove instrument cluster and inspect instrument cluster printed circuit.
  • Remove instrument cluster gauge amplifier and connect a jumper wire from Gauge Tester directly to fuel gauge 'SIG' terminal.
  • Install instrument cluster.
  • Turn ignition switch to RUN position and read fuel gauge .
  • Does fuel gauge read EMPTY?
Yes
REPLACE instrument cluster gauge amplifier . RESTORE vehicle. RETEST system.

No
REPLACE fuel gauge . INSTALL instrument cluster gauge amplifier . RESTORE vehicle. RETEST system.

 

B8 CHECK TEST BOX (HIGH)

  • Turn ignition switch to OFF position.
  • With Rotunda Gauge System Tester 021-00055 or equivalent connected as in Step D1, set tester to 145 ohms.
  • Turn ignition switch to RUN position.
  • Wait 60 seconds and read fuel gauge .
  • Does fuel gauge read FULL?
Yes
GO to B10.

No
GO to B9.

 

B9 ANTI-SLOSH MODULE BYPASS TEST

  • Turn ignition switch to OFF position.
  • Remove instrument cluster and inspect instrument cluster printed circuit.
  • Remove instrument cluster gauge amplifier.
  • Connect a jumper wire from tester to fuel gauge 'SIG' terminal.
  • Turn ignition switch to RUN position and read fuel gauge .
  • Does fuel gauge read FULL?
Yes
REPLACE instrument cluster gauge amplifier . RESTORE vehicle. RETEST system.

No
REPLACE fuel gauge . RESTORE vehicle. RETEST system.

 

B10 INSPECT FUEL TANK

  • Inspect fuel tank for damage or distortion.
  • Is there damage?
Yes
REPLACE fuel tank . RESTORE vehicle. RETEST system.

No
GO to B11.

 

B11 CHECK TEST BOX - EMPTY STOP

  • Connect one lead of Digital Volt-Ohmmeter 007-00001 or equivalent to the fuel sender signal lead and the other lead to ground.

    NOTE: Float rod is against empty stop (closest to filter).

  • Does ohmmeter read between 14-18 ohms?
Yes
GO to B12 .

No
REPLACE fuel tank sending unit . RESTORE vehicle. RETEST system.

 

B12 CHECK TEST BOX - FULL STOP

  • Connect one lead of Digital Volt-Ohmmeter 007-00001 or equivalent to the fuel sender signal lead and the other lead to sender ground.

    NOTE: Float rod is against full stop.

  • Does ohmmeter read between 155-165 ohms?
Yes
GO to B13 .

No
REPLACE fuel tank sending unit . RESTORE vehicle. RETEST system.

 

B13 CHECK FLOAT ROD LEVEL

  • Connect one lead to Digital Volt-Ohmmeter 007-00001 or equivalent to the fuel sender signal lead and the other lead to sender ground.
  • Slowly move float rod from full stop to empty stop.
  • Does ohmmeter reading slowly decrease?
Yes
GO to B14 .

No
REPLACE fuel tank sending unit . RESTORE vehicle. RETEST system.

 

B14 CHECK ANTI-SLOSH/LOW FUEL WARNING

  • Turn ignition switch to the OFF position.
  • Connect Rotunda Instrument Gauge System Tester 021-00055 or equivalent in sender circuit.
  • Disconnect Circuit rear lamp wiring connector under instrument panel and connect tester to cluster side of connector.
  • Set tester to 56 ohms.
  • Turn ignition switch to the RUN position, wait 60 seconds.
  • Is low fuel indicator on?
Yes
REPLACE instrument cluster gauge amplifier /low fuel warning module. RESTORE vehicle. RETEST system.

No
GO to B15 .

 

B15 CHECK GAUGE AND INDICATOR

  • Turn ignition switch to the OFF position.
  • Reset tester to 33 ohms.
  • Turn ignition switch to the RUN position.
  • Wait 60 seconds.
  • Is indicator on, and gauge showing 1/8 tank?
Yes
Instrument cluster gauge amplifier operating properly. RESTORE vehicle. RETEST system.

No
GO to B16 .

 

B16 CHECK INDICATOR

  • With ignition switch in the ON position, ground indicator circuit between indicator and low fuel level warning switch .
  • Is indicator on?
Yes
REPLACE instrument cluster gauge amplifier . RESTORE vehicle. RETEST system.

No
GO to B17 .

 

B17 CHECK INDICATOR BULB

  • Turn ignition switch switch off.
  • Remove instrument cluster as outlined.
  • Remove indicator bulb using an ohmmeter check bulb continuity.
  • Does bulb test OK?
Yes
REPLACE instrument cluster printed circuit . RESTORE vehicle. RETEST system.

No
REPLACE damaged indicator bulb. RESTORE vehicle. RETEST system.

  

PINPOINT TEST C: COOLANT TEMPERATURE READS ERRONEOUSLY

 

C1 CHECK POWER AT CLUSTER

  • Turn ignition switch to the OFF position.
  • Partially remove instrument cluster .
  • Turn ignition switch to RUN position.
  • Using a voltmeter check for voltage at cluster connector pin per chart.

    Connector Pin Circuit Function
    J1 16 640 (R/Y) Ignition Voltage
    J1 15 563 (O/Y) Gauge Ground
    J1 14 39 (R/W) Coolant Temp Input

  • Is system voltage present?
Yes
GO to C2.

No
SERVICE Circuit 640 (R/Y) for open circuit. RESTORE vehicle. RETEST system.

 

C2 CHECK CLUSTER GROUND

  • Using an ohmmeter connected to a known good ground, connect other end to ground circuit per chart above.
  • Is resistance .5 ohms or less?
Yes
GO to C3.

No
SERVICE Circuit 563 (O/Y) for open circuit. RESTORE vehicle. RETEST system.

 

C3 CHECK SENDER UNIT CIRCUIT AT LOW

  • Insert Rotunda Instrument Gauge, System Tester 021-00055 or equivalent. Disconnect connector at water temperature indicator sender unit and connect tester to cluster side of connector. Set to 74 ohms.
  • Turn ignition switch to RUN position.
  • Does gauge read cold?
Yes
GO to C4.

No
GO to C5.

 

C4 CHECK SENDER UNIT CIRCUIT AT HIGH

  • Set Gauge System Tester to 10 ohms.
  • Does gauge read hot?
Yes
REPLACE water temperature indicator sender unit . RESTORE vehicle. RETEST system.

No
GO to C5.

 

C5 CHECK COOLANT TEMPERATURE INPUT CIRCUIT

  • With ignition switch in the RUN position, using a test lamp connected to known good ground, connect probe to sending unit connector.
  • Did test lamp illuminate?
Yes
GO to C7.

No
GO to C6.

 

C6 CHECK CIRCUIT 39 (R/W)

  • Turn ignition switch to OFF position. Remove instrument cluster as outlined.
  • Turn ignition switch to RUN position. Using test lamp check Circuit 39 (R/W) at instrument cluster connector per chart.

    Connector Pin Circuit Function
    J1 16 640 (R/Y) Ignition Voltage
    J1 15 563 (O/Y) Gauge Ground
    J1 14 39 (R/W) Coolant Temp Input

  • Did test lamp illuminate?
Yes
SERVICE Circuit 39 (R/W) for open circuit. RESTORE vehicle. RETEST system.

No
GO to C7.

 

C7 CHECK COOLANT TEMPERATURE GAUGE

  • Turn ignition switch to OFF position.
  • Disconnect cluster connectors.
  • Using an ohmmeter, check gauge for continuity at contact clips.
  • Is there continuity at all clips?
Yes
GO to C8.

No
REPLACE instrument cluster temperature gauge . RESTORE vehicle. RETEST system.

 

C8 CHECK PRINTED CIRCUIT

  • Reconnect cluster connectors.
  • Using an ohmmeter, check for continuity from gauge contact clips to cluster connectors per chart.

    Connector Pin Circuit Function
    J1 16 640 (R/Y) Ignition Voltage
    J1 15 563 (O/Y)) Gauge Ground
    J1 14 39 (R/W) Coolant Temp Input

  • Is there continuity at all circuits?
Yes
REPLACE instrument cluster temperature gauge . RESTORE vehicle. RETEST system.

No
REPLACE instrument cluster printed circuit . RESTORE vehicle. RETEST system.

  

PINPOINT TEST D: OIL PRESSURE READS ERRONEOUSLY

 

D1 CHECK POWER AT CLUSTER

  • Turn ignition switch to the OFF position.
  • Partially remove instrument cluster .
  • Turn ignition switch to RUN position.
  • Using a voltmeter check for voltage at cluster connector pin per chart.

    Connector Pin Circuit Function
    J2 4 640 (R/Y) Ignition Voltage
    J2 3 875 (BK/LB) Gauge Ground
    J2 2 31 (W/R) Oil Pressure Input

  • Is system voltage present?
Yes
GO to D2.

No
SERVICE Circuit 640 (R/Y) for open circuit. RESTORE vehicle. RETEST system.

 

D2 TEST SENDER CIRCUIT AT LOW

  • Place ignition switch in the ON position with engine OFF. Observe gauge performance.
  • Does gauge read "L" or below?
Yes
GO to D3.

No
GO to D4.

 

D3 CHECK GAUGE RESPONSE

  • Disconnect oil pressure sender and short the lead to engine ground.
  • Does gauge indicate mid-scale or slightly above mid-scale?
Yes
REPLACE oil pressure sender . RESTORE vehicle. RETEST system.

No
GO to D4.

 

D4 CHECK CIRCUIT 31 (W/R)

  • Leave oil pressure input circuit shorted to ground.
  • Turn ignition switch to the OFF position. Remove instrument cluster as outlined.
  • Using an ohmmeter connected to a known good ground, connect second lead to Connector J2, Pin 2. Measure resistance.
  • Is resistance .5 ohms or less?
Yes
GO to D5.

No
SERVICE Circuit 31 (W/R) for open circuit. RESTORE vehicle. RETEST system.

 

D5 CHECK OIL PRESSURE GAUGE

  • Disconnect instrument cluster connectors.
  • Using an ohmmeter check gauge for continuity at contact clips.
  • Is there continuity at all clips?
Yes
GO to D6.

No
REPLACE oil pressure gauge . RESTORE vehicle. RETEST system.

 

D6 CHECK PRINTED CIRCUIT

  • Reconnect cluster connectors.
  • Using an ohmmeter check for continuity from gauge contact clips to cluster connectors per chart.

    Connector Pin Circuit Function
    J2 4 640 (R/Y) Ignition Voltage
    J2 3 875 (BK/LB) Gauge Ground
    J2 2 31 (W/R) Oil Pressure Input

  • Is there continuity at all circuits?
Yes
REPLACE oil pressure gauge . RESTORE vehicle. RETEST system.

No
REPLACE instrument cluster printed circuit . RESTORE vehicle. RETEST system.

  

PINPOINT TEST E: CHARGE INDICATION READS ERRONEOUSLY

 

E1 LAMP CHECK NO. 1

  • Engine OFF.
  • Key in OFF position.
  • Is charge indicator on?
Yes
REFER to Section 14-00. SERVICE as necessary.

No
GO to E2.

 

E2 LAMP CHECK NO. 2

  • Engine OFF.
  • Key in RUN position.
  • Is charge indicator on?
Yes
GO to E3.

No
GO to E4.

 

E3 LAMP CHECK NO. 3

  • Key in RUN position.
  • Engine running.
  • Is charge indicator on?
Yes
GO to E6.

No
Lamp test complete and operational.

 

E4 INOPERATIVE INDICATOR LAMP

  • Key in ON position.
  • Engine OFF.
  • Disconnect regulator connector and ground 'I' terminal.
  • Is charge indicator on?




Yes
REFER to Section 14-02. SERVICE as necessary.

No
GO to E5.

 

E5 CHECK CIRCUIT 904 (LG/R) FOR OPEN

  • Turn ignition switch to the OFF position.
  • Remove instrument cluster as outlined.
  • Using an ohmmeter connected to a known good ground, connect second lead to pin per chart.
  • Measure resistance.

    CONNECTOR J1
    Pin Circuit Function
    10 904 (LG/R) Charge Indicator Input

  • Is resistance 5 ohms or less?
Yes
REMOVE jumper wire. GO to E6.

No
SERVICE Circuit 904 (LG/R) for OPEN circuit. RESTORE vehicle. RETEST system.

 

E6 CHECK CIRCUIT 904 (LG/R) FOR SHORT

  • Disconnect instrument cluster connectors.
  • Disconnect voltage regulator connector.
  • Using an ohmmeter connected to a known good ground, connect second lead to pin per chart.
  • Measure resistance.

    CONNECTOR J1
    Pin Circuit Function
    10 904 (LG/R) Charge Indicator Input

  • Is resistance 5 ohms or less?
Yes
SERVICE Circuit 904 (LG/R) for open circuit. RESTORE vehicle. RETEST system.

No
GO to E7.

 

E7 CHECK CIRCUIT 16 (R/LG) FOR VOLTAGE

  • Turn ignition switch to the RUN position.
  • Using a test lamp connected to a known good ground, connect other end to pin per chart.

    CONNECTOR J1
    Pin Circuit Function
    11 16 (R/LG) Charge Indicator Input

  • Did test lamp illuminate?
Yes
GO to E8.

No
SERVICE Circuit 16 (R/LG) for open circuit. RESTORE vehicle. RETEST system.

 

E8 CHECK CHARGE INDICATOR LAMP

  • Remove charge indicator lamp bulb.
  • Using an ohmmeter, check continuity of bulb.
  • Is bulb continuity OK?
Yes
REPLACE instrument cluster printed circuit . RESTORE vehicle. RETEST system.

No
REPLACE damaged bulb. RESTORE vehicle. RETEST system.

  

PINPOINT TEST F: SPEEDOMETER READS ERRONEOUSLY

 

F1 CHECK SPEED SIGNAL 

  • Raise drive wheels off the ground.
  • Disconnect vehicle speed sensor connector.
  • Connect an AC voltmeter between the two output pins on the automatic transmission mounted vehicle speed sensor (VSS).
  • Operate vehicle.
  • Is voltage between 1.3-6.1 volts AC?
Yes
GO to F4.

No
GO to F2.

 

F2 CHECK DRIVEN GEAR

  • Disconnect vehicle speed sensor (VSS) from automatic transmission. Verify presence of speedometer gear with all teeth in good condition and presence of retainer clip.
  • Are driven gear teeth OK and is clip present?
Yes
GO to F3.

No
REPLACE with proper speedometer gear and/or clip. RESTORE vehicle. RETEST system.

 

F3 CHECK DRIVE GEAR

  • Verify presence of speedometer drive gear on output shaft .
  • Is drive gear present?
Yes
GO to F4.

No
SERVICE transmission as necessary. RESTORE vehicle. RETEST system.

 

F4 CHECK CIRCUIT 679 (GY/BK) FOR SHORT TO GROUND

  • Turn ignition switch to the OFF position.
  • Remove instrument cluster as outlined.
  • Using an ohmmeter connected to a known good ground, connect second lead to Circuit 679 (GY/BK) per chart.
  • Measure resistance.

    Conn: Pin Circuit Function
    J1 4 54 (LG/Y) Power Input
    J1 6 676 (PK/O) Vehicle Speed Input (-)
    J1 7 640 (R/Y) Power Input
    J1 5 679 (GY/BK) Vehicle Speed Input (+)

  • Is resistance 5 ohms or less?
Yes
SERVICE Circuit 679 (GY/BK) for short. RESTORE vehicle. RETEST system.

No
Leave ohmmeter connected to Circuit 679 (GY/BK). GO to F5.

 

F5 CHECK CIRCUIT 679 (GY/BK) FOR OPEN CIRCUIT

  • Using a jumper wire connected to a known good ground, connect other end to Circuit 679 (GY/BK) at vehicle speed sensor connector.
  • Measure resistance.
  • Is resistance 300 ohms or less?
Yes
GO to F6.

No
SERVICE Circuit 679 (GY/BK) for open circuit. RESTORE vehicle. RETEST system.

 

F6 CHECK CIRCUIT 676 (PK/O)

  • Disconnect ohmmeter from Circuit 679 (GY/BK), connect ohmmeter to Circuit 676 (PK/O) per chart.
  • Measure resistance to known good ground.

    Conn: Pin Circuit Function
    J1 4 54 (LG/Y) Power Input
    J1 7 640 (R/Y) Power Input
    J1 6 676 (PK/O) Vehicle Speed Input (-)
    J1 5 679 (GY/BK) Vehicle Speed Input (+)

  • Is resistance 5 ohms or less?
Yes
GO to F7.

No
SERVICE Circuit 676 (PK/O) for open circuit. RESTORE vehicle. RETEST system.

 

F7 CHECK CLIP TO CLUSTER CIRCUIT CONNECTOR

  • Disconnect instrument cluster connectors.
  • Using ohmmeter check speedometer for continuity from contact clips to printed circuit.
  • Is there continuity at all clips?
Yes
GO to F8.

No
REPLACE contact clips. RESTORE vehicle. RETEST system.

 

F8 CHECK PRINTED CIRCUIT

  • Reconnect cluster connectors.
  • Using an ohmmeter check for continuity from speedometer contact clips to cluster connectors per chart.

    Conn: Pin Circuit Function
    J1 4 54 (LG/Y) Power Input
    J1 7 640 (R/Y) Power Input
    J1 6 676 (PK/O) Vehicle Speed Input (-)
    J1 5 679 (GY/BK) Vehicle Speed Input (+)

  • Is there continuity at all circuits?
Yes
REPLACE speedometer/tachometer assembly. RESTORE vehicle. RETEST system.

No
REPLACE instrument cluster printed circuit . RESTORE vehicle. RETEST system.

  

PINPOINT TEST G: ODOMETER READS ERRONEOUSLY

 

G1 CHECK SPEEDOMETER

  • Road test vehicle.
  • Is speedometer operating?
Yes
GO to G2.

No
GO to Pinpoint Test Step F1.

 

G2 CHECK ODOMETER

  • Drive vehicle over a known distance.
  • Is odometer reading accurately?
Yes
System OK.

No
REPLACE speedometer/tachometer assembly.

  

PINPOINT TEST H: TACHOMETER NOT REFLECTING ENGINE SPEED

 

H1 CHECK SUPPLY TO GAUGE

  • Turn ignition switch to OFF position.
  • Partially remove instrument cluster panel , as outlined, to gain access to the cluster connectors.
  • Turn ignition switch to the RUN position.
  • Using a voltmeter check voltage at Circuit 640 (R/Y) at Connector J2, Pin 4.
  • Is battery voltage present?
Yes
GO to H2.

No
SERVICE Circuit 640 (R/Y) for open. RESTORE vehicle. RETEST system.

 

H2 CHECK GAUGE GROUND

  • Using an ohmmeter connected to a known good ground, connect second lead to Circuit 397 (BK/W) and 651 (BK/Y) at Connector J2, Pin 9 and Pin 11.
  • Measure resistances.
  • Are resistances 5 ohms or less?
Yes
GO to H3.

No
SERVICE Circuit 397 (BK/W) and 651 (BK/Y) for open. RESTORE vehicle. RETEST system.

 

H3 CHECK TACHOMETER INPUT CIRCUIT

  • Turn ignition switch to OFF position.
  • Disconnect cluster Connector J2.
  • Disconnect ignition coil, or DIS.
  • Using an ohmmeter, measure resistance of Circuit 11 (T/Y) from ignition coil Connector or DIS Connector to cluster J2 Connector.
  • Is resistance 1.8K ohms or less?
Yes
GO to H4.

No
SERVICE Circuit 11 (T/Y) for open. RESTORE vehicle. RETEST system.

 

H4 CHECK CLUSTER CLIP TO CLUSTER CIRCUIT CONNECTION

  • Reconnect cluster Connector J2.
  • Using an ohmmeter check for continuity from the tachometer connector clips to instrument cluster printed circuit.
  • Is there continuity?
Yes
GO to H5.

No
REPLACE connector clips. RESTORE vehicle. RETEST system.

 

H5 CHECK PRINTED CIRCUIT

  • Using an ohmmeter, check each circuit listed below for continuity from gauge connector clips to cluster Connector J2.

    Conn: Pin Circuit Function
    J2 1 397 (BK/W) and
    651 (BK/Y)    		 Ground
    J2 8 640 (R/Y) Run/Start Power
    J2 10 11 (T/Y) Tachometer Input

  • Is there continuity at all circuits?
Yes
REPLACE speedometer/tachometer assembly. RESTORE vehicle. RETEST system.

No
REPLACE instrument cluster printed circuit . RESTORE vehicle. RETEST system.

  

PINPOINT TEST I: ALL WARNING INDICATORS INOPERATIVE

 

I1 CHECK CLUSTER GROUND

  • Turn ignition switch to OFF position.
  • Partially remove instrument cluster as outlined.
  • Using an ohmmeter connected to a known good ground, connect second lead to Circuit 57 (BK) at connector J1, Pin 12.
  • Measure resistance.
  • Is resistance 5 ohms or less?
Yes
GO to I2.

No
SERVICE Circuit 57 (BK) for open. RESTORE vehicle. RETEST system.

 

I2 CHECK SUPPLY AT CLUSTER

  • Turn ignition switch to RUN position.
  • Using a test lamp check Circuits 54 (LG/Y) and 640 (R/Y) at Connector J1.
  • Did test lamp illuminate?
Yes
REPLACE instrument cluster printed circuit . RESTORE vehicle. RETEST system.

No
SERVICE Circuits 54 (LG/Y) or 640 (R/Y) for open. RESTORE vehicle. RETEST system.

  

PINPOINT TEST J: LOW COOLANT LEVEL INDICATION NOT OPERATING PROPERLY

 

J1 CHECK COOLANT LEVEL

  • When the engine is cold, observe level of coolant in radiator coolant recovery reservoir .
  • Is coolant level below FULL HOT mark?
Yes
GO to J2.

No
GO to J3.

 

J2 CHECK COOLANT LEVEL—ENGINE RUNNING

  • Fill coolant to the FULL HOT mark on the radiator coolant recovery reservoir .
  • Start vehicle and observe low coolant indicator .
  • Does low coolant indicator illuminate then stay off?
Yes
System OK.

No
GO to J3.

 

J3 CHECK INDICATOR WIRING

  • Turn ignition to RUN.
  • Using a jumper wire, ground Circuit 794 (LB) wire at instrument cluster.
  • Does indicator turn on?
Yes
GO to J5.

No
GO to J4.

 

J4 CHECK INDICATOR

  • Turn ignition switch to RUN.
  • Using a jumper wire, ground Circuit 794 (LB) wire at instrument cluster .
  • Does indicator turn ON?
Yes
SERVICE Circuit 794 (LB).

No
SERVICE low coolant level warning sensor .

 

J5 CHECK VOLTAGE TO SENSOR CIRCUIT 640 (R/Y)

  • Measure voltage on Circuit 640 (R/Y) at low coolant level warning sensor .
  • Is voltage at least 10 volts?
Yes
SERVICE low coolant warning sensor or Circuit 57 (BK).

No
SERVICE Circuit 640 (R/Y).