Ford Mustang (1999-2004) Service Manual: Instrument Cluster Replacement

When it is necessary to install a new instrument cluster, contact the Instrument Cluster Program.

Gauge Indication Systems

Tachometer

Engine rpm information is relayed to the instrument cluster from the powertrain control module (PCM) over the standard corporate protocol (SCP) network.

Speedometer

The instrument cluster receives the vehicle speed signal from the PCM over the SCP network and displays it on the speedometer gauge. If the instrument cluster receives no vehicle speed signal after one second, the speedometer defaults to 0.0 km/h (0.0 mph).

Odometer

The instrument cluster receives an odometer message from the PCM and stores the mileage in memory. When the instrument cluster fails to receive the odometer message for more than two seconds, the odometer will display dashes.

Fuel Gauge

The fuel sender is hardwired to the fuel gauge. When the instrument cluster fails to receive the fuel level signal for more than 33 seconds, the fuel level gauge will move below E (empty). If the fuel level signal operates correctly for more than 33 seconds, the fuel gauge will return to the correct position.

Fuel fills of less than 9.5 liters (2.5 gallons) require at least 10 minutes to update the fuel gauge indication.

Engine Coolant Temperature Gauge

Engine coolant temperature information is received by the instrument cluster from the PCM over the SCP network. Engine coolant temperatures above 121C (250F) will cause the gauge to indicate above the normal band. If the engine coolant temperature information is missing or invalid for five seconds, the temperature gauge will indicate below the cold (C) position.

Voltage Gauge (except Cobra)

The voltage gauge displays the system voltage as measured at the instrument cluster run input.

Boost Gauge (Cobra only)

The boost pressure gauge on the instrument cluster receives and measures the boost pressure directly from the intake manifold. The boost pressure gauge will display between 0.0-0.48 kpa (0.0-10 psi) boost pressure dependent upon accelerator position, engine load, and engine rpm.

LOW FUEL Level Indicator

The low fuel level indicator is hardwired from the fuel sender to the instrument cluster. The instrument cluster will illuminate the low fuel indicator when the usable fuel quantity is less than 1/8 tank (15%) of fuel tank capacity.

Oil Pressure Gauge

The oil pressure gauge is hardwired from the oil pressure switch to the instrument cluster. The oil pressure gauge will indicate either normal or no oil pressure.

CHECK FUEL CAP

The CHECK FUEL CAP indicator is used to indicate significant leaks in the fuel tank evaporative system due to a loose fuel cap. Fuel tank pressure is monitored by the PCM. If a leak is detected the PCM signals a fault to the instrument cluster via the SCP network. Once the PCM has detected a loose fuel cap and the CHECK FUEL CAP indicator is illuminated, the indicator will remain illuminated until the fuel cap is secured and the vehicle has been running for several minutes. For additional information, refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.

BRAKE Warning Indicator

The BRAKE warning indicator activates when the generic electronic module (GEM) detects the ignition switch circuits are in the RUN state, when the GEM detects low brake fluid level, or that the parking brake is applied. The BRAKE warning indicator will prove out starting when the GEM detects that the ignition circuits have made a transition to RUN or START from OFF, ACC, or keyout and ending when either three seconds have elapsed or when the GEM detects the ignition circuits have made a transition to OFF, ACC, or keyout.

Safety Belt Warning Indicator

The safety belt switch is hardwired to the GEM. The safety belt warning indicator will be illuminated when the GEM sends a ground signal to the instrument cluster.

ABS Warning Indicator

The ABS warning indicator will be illuminated when the anti-lock brake control module sends a ground signal to the instrument cluster. The prove-out of the ABS indicator is controlled by the anti-lock brake control module.

SERVICE ENGINE SOON Indicator

The SERVICE ENGINE SOON indicator receives its signal from the PCM over the SCP network. If the instrument cluster does not receive a message from the PCM within five seconds, the instrument cluster will illuminate the SERVICE ENGINE SOON indicator and log a diagnostic trouble code (DTC).

High Beam Indicator

The high beam indicator will illuminate when the steering column multifunction switch is in the high beam position by sending a battery signal to the instrument cluster.

Right and Left Turn Indicator

The right and left turn indicators will illuminate when the steering column multifunction switch is in either turn signal position or hazard lamps position by sending a battery signal to the instrument cluster.

AIR BAG Warning Indicator

The AIR BAG warning indicator will be illuminated when the restraint control module (RCM) sends a ground signal to the instrument cluster. The prove-out of the AIR BAG warning indicator is controlled by the RCM.

THEFT Indicator

The THEFT indicator provides a passive anti-theft system (PATS) prove-out. The THEFT indicator will prove out for three seconds following the ignition switch cycle and will flash following an ignition switch OFF transition to indicate that PATS is active.

Charging System Indicator

The charging system indicator will be illuminated when the generator provides a ground signal to the instrument cluster. The instrument cluster provides a prove-out when the ignition switch is in the RUN position with the engine off. When the engine is started, the generator removes the ground to the instrument cluster and extinguishes the charging system indicator.

Overdrive Off (O/D OFF) Indicator

The O/D OFF indicator is controlled by the off/on message sent from the PCM over the SCP network.

The instrument cluster does not provide a prove-out for the O/D OFF indicator, but will remain illuminated if the overdrive has been commanded off following the instrument cluster prove-out.

Traction Control Indicator

During initialization, the instrument cluster will receive the traction control system state status message from the traction control module to determine if the vehicle is equipped with traction control. If the vehicle is equipped with traction control, this information will be stored in random access memory (RAM) and the indicator will prove out for three seconds during each ignition cycle. If this message is not received, the instrument cluster will assume that the vehicle is not traction control equipped and the indicator will remain off. When the traction control is active, the traction control module sends the instrument cluster a traction control active signal and the instrument cluster illuminates the traction control indicator. When the traction control is inactive, the traction control module removes the traction control active signal and the instrument cluster turns off the indicator.

In the event of a traction control failure, the traction control indicator will remain off and the ABS indicator will illuminate.