Tachometer; Speedometer; Odometer; Fuel Gauge - Ford Mustang 2005 Workshop Manual

2005 Mustang Workshop Manual
electronic throttle control (ETC) warning indicator (3 seconds)

Tachometer

The instrument cluster receives the tachometer data from the powertrain control module (PCM) over the communication network and commands the tachometer pointer between 0 and
7,000 rpm (4.0L engines), or between 0 and 8,000 rpm (4.6L engines) according to the data.

Speedometer

The instrument cluster receives the vehicle speed information from the PCM over the communication network and displays it on the speedometer gauge. If the instrument cluster receives
no vehicle speed signal after 1 second, the speedometer defaults to 0.

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
2 seconds, the odometer displays dashes.

Fuel Gauge

The instrument cluster receives the fuel level signal from the smart junction box (SJB) that reads the 2 fuel level sensors. The fuel level sensor measures variable resistance in the fuel
tank depending on the current fuel level. When the fuel level is low, the resistance in the unit is low (15 ohms ± 2 ohms). When the fuel level is high, the resistance in the unit is high (160
ohms ± 4 ohms).
The instrument cluster uses 4 different operating modes to calculate the fuel level:
Key OFF fueling
Anti-slosh (default mode)
Key ON fueling
Recovery
After a fuel fill up, the time for the fuel gauge to move from empty (E) to full (F) ranges from 2 seconds to 55 minutes depending on which operating mode the fuel gauge is in.
The key OFF fueling mode (2 seconds to read empty [E] to full [F]) requires 3 conditions be met:
The key must be in the OFF position throughout the entire refueling of the vehicle.
At least 15% of the vehicle's fuel capacity must be added to the fuel tank.
The instrument cluster must receive a valid key ON fuel sender reading within 1 second of the key being put into the RUN position. The key ON sample readings are considered
valid if the fuel sender reading is between 15 ohms ± 2 ohms and 160 ohms ± 4 ohms.
If these conditions are not met, the fuel gauge stays in the anti-slosh mode, which results in a slow to read full (F) event.
The default fuel gauge mode is called the anti-slosh mode. To prevent fuel gauge changes from fuel slosh (gauge instability due to changes in fuel sender readings caused by fuel moving
around in the tank), the fuel gauge takes approximately 55 minutes to go from empty (E) to full (F).
The key ON fueling mode (approximately 90 seconds to read empty [E] to full [F]) requires 3 conditions be met:
The transmission is in PARK (P) (automatic transmission), or the parking brake applied (manual transmission).
The key is in the RUN position.
At least 15% of the vehicle's fuel capacity must be added to the fuel tank.
In key ON fueling mode, a 30-second timer activates after the transmission is put into the PARK (P) position (automatic transmission) or when the parking brake is applied (manual
transmission). When the 30-second time has elapsed and at least 15% of the vehicle's fuel capacity has been added, the fuel gauge response time is 90 seconds to read from empty (E)
to full (F). When the transmission is shifted out of PARK (P) or the parking brake is released, the fuel gauge strategy reverts to the anti-slosh mode. The key ON fueling mode prevents
slow to read full events from happening if the customer refuels the vehicle with the key in the RUN position.
Recovery mode is incorporated into the instrument cluster strategy to recover from a missing fuel level input during a refueling event. Missing fuel level inputs result from intermittent
opens in the fuel sender or its circuits. Recovery mode (empty [E] to full [F] approximately 20 minutes) is initiated when the following 2 conditions are met:
The instrument cluster is in the anti-slosh (default) mode.
The actual fuel level in the tank is greater than what is being displayed by the fuel gauge.

Engine Coolant Temperature Gauge

The PCM receives the engine coolant temperature status through hardwired circuitry to the engine coolant temperature (ECT) sensor. The instrument cluster receives the engine coolant
temperature data from the PCM over the communication network. The instrument cluster monitors the engine coolant temperature data received from the PCM and commands the engine
coolant temperature gauge pointer.
Voltage Gauge
The voltage gauge displays the system battery voltage as measured at the instrument cluster run input circuit.

Oil Pressure Gauge

The SJB is hardwired to the oil pressure switch. The oil pressure switch unit consists of a diaphragm and contact points, which are normally open. When there is low (under 41 kPa [6 psi])
or no oil pressure, the oil pressure switch remains open, removing the ground to the SJB. When sufficient oil pressure exists, the oil pressure switch closes providing a ground signal to
the SJB. The SJB monitors the oil pressure ground signal and sends a message to the instrument cluster to operate the oil pressure gauge according to the engine oil pressure.
Low Fuel Warning Indicator
The low fuel warning indicator is controlled by the instrument cluster and warns the driver when the fuel level is 1/16 of a tank or lower.
Check Fuel Cap Warning Indicator
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11/14/2009