Instrument Panels Audi A4 B5

DESCRIPTION & OPERATION

Some vehicles are equipped with an Auto-Check system that monitors the condition of various vehicle systems. When a fault occurs in one of these systems, a symbol is displayed in the Auto-Check display window between the tachometer and speedometer. Radio and tape player information is also displayed in this window. Indicator lights in the instrument cluster are of 2 types: those that are part of the Auto-Check system and those that are not.

Some vehicles are equipped with a trip computer that records trip information (fuel consumption, etc.). When requested, this information is displayed in the trip computer display window in the center of the instrument cluster. The function control switches (rocker switch and RESET button) for the trip computer are on the right side of the steering column, on the end of the windshield wiper control lever.

AUTO-CHECK SYSTEM

When ignition is on (engine off), the OK indicator in the Auto-Check display area illuminates for a few seconds. This indicates all monitored systems are okay (this also checks Red and Yellow display bulbs). The Auto-Check system then continues to monitor these systems when the engine is started and while the vehicle is driven. System malfunctions are classified into 2 groups: DANGER display and WARNING display.

DANGER Display

When a condition that indicates an urgent need for repairs occurs, a buzzer sounds 3 times and the appropriate Red symbol is displayed, indicating one of the following conditions exists

1. Engine coolant level is low or engine coolant temperature is high (same symbol is used to indicate either condition)
2. Engine oil pressure is low.

When more than one malfunction occurs, only one symbol is displayed. Malfunctions are not stored in system memory.

WARNING Display

When a condition that indicates a less urgent need for repairs occurs, a buzzer sounds once and the appropriate Yellow symbol is displayed, indicating one of the following conditions exists

1. Brakelights are inoperative
2. Brake pads worn out (indicated by a circle within parenthesis)
3. Charging system voltage is low or high
4. Fuel level is low
5. Low beam headlight or taillight is inoperative
6. Windshield washer fluid level is low.

TRIP COMPUTER

Two switches control the functions of the trip computer: a rocker switch and a RESET button, both located on the end of the windshield wiper control lever. To display trip information, turn ignition on. Press the rocker switch in either direction (switch direction determines which functions will be displayed). Arrow inside the display window points to symbol (or letters) above and below display panel. See IDENTIFYING SYMBOLS FOR TRIP COMPUTER FUNCTIONS table. The number displayed in the window applies to the particular function to which the arrow points.

IDENTIFYING SYMBOLS FOR TRIP COMPUTER FUNCTIONS

Instantaneous Fuel Consumption

Displays what the computer calculates to be the vehicle's gas mileage for the immediate driving conditions (this function is different than the average fuel consumption function, which is calculated over a longer period of time). Every 100 feet of travel, the computer measures the amount of fuel instantaneously consumed and displays this figure in miles per gallon. When the vehicle is decelerating and the deceleration fuel shut-off system engages, 3 dashes are displayed instead of a number.

Miles-To-Empty

Displays how many miles the vehicle can be driven with the amount of fuel left in the tank. The number displayed is made current every 5 miles. The computer bases this figure on the average amount of fuel consumed in the last 20 miles of driving. When the fuel reserve is less than about 30 miles to empty, a fuel reserve alert function causes the display to begin blinking and revert to the miles-to-empty function. However, if the fuel reserve is less than about 1.3 gallons, the letter "E" (Empty) will blink instead. Pressing the RESET button or the rocker switch stops the blinking.

Fuel Consumption Per Trip

Displays the gallons of fuel consumed while driving. When ignition is turned off and the engine is restarted, previously recorded data is erased (zero is displayed) after vehicle is driven 100 feet. Pressing RESET button also erases data.

Driving Time

Driving time, which is accrued while engine is running, remains stored in memory after ignition is turned off. While driving, the computer will switch to driving time display and blink every 2 hours, alerting driver to take a break. Push RESET button for 2 seconds to return the display to zero. Maximum driving time that can be stored is 23 hours and 59 minutes.

Average Fuel Consumption

Displays the average fuel economy in miles per gallon since the last RESET. To delete stored data, press RESET.

Average Driving Speed

Displays the average driving speed in miles per hour since the last RESET. To delete stored data, push RESET.

AUTO-CHECK SYSTEM TEST

Information not available at time of publication.

COOLANT TEMPERATURE GAUGE TEST

1. Disconnect 4-wire connector from electronic thermoswitch, located on coolant pipe behind cylinder head. Connect Gauge Tester (VW 1301) between terminal "T" of electronic thermoswitch connector and engine ground. (Scheme 1)
2. Set gauge tester dial to 560. Turn ignition on. Note 2 dots, one on each side of cold mark on gauge. If fuel gauge needle falls within these 2 dots, go to next step. If fuel gauge needle does not fall within these 2 dots, go to step 5).
3. Set gauge tester dial to 58. Note 2 dots, one on each side of mark that is just past halfway mark on gauge. If fuel gauge needle falls within these 2 dots, gauge is okay. If fuel gauge needle does not fall within these 2 dots, go to next step.
4. Check wiring. If wiring is okay, check voltage regulator. See «VOLTAGE REGULATOR TEST»(/audi/a4/b5-1994-1999/remont/gauges-instrument-panels/#instrument-panels__voltage-regulator-test). If voltage regulator is okay, replace coolant temperature gauge.

Scheme 1

COOLANT OVERHEAT WARNING SYMBOL

1. Disconnect 4-wire connector from electronic thermoswitch, located on coolant pipe behind cylinder head. Connect Gauge Tester (VW 1301) between terminal "C" of electronic thermoswitch connector and engine ground. (Scheme 1)
2. Start engine. If warning symbol is displayed after about 30 seconds, system is okay. If warning symbol is not displayed after about 30 seconds, check wiring. If wiring is okay, replace instrument cluster board.

FUEL GAUGE TEST

1. Disconnect fuel gauge sending unit connector at fuel tank (accessible through luggage compartment floor). Connect Gauge Tester (VW 1301) to fuel gauge sending unit connector terminals. (Scheme 2) Set tester dial at 58 (this provides a resistance of 40 ohms). Turn ignition on. If gauge does not read FULL, go to next step. If gauge reads FULL, replace fuel gauge sending unit.
2. Turn ignition off. Leave tester connected to fuel gauge sending unit connector terminals. Remove instrument cluster. Disconnect both instrument cluster 26-pin wiring harness connectors. (Scheme 3)and (Scheme 4). Inspect connector terminals for damage and repair as necessary.
3. Connect Red 26-pin connector to Circuit Tester (VAG 1598). Reconnect Green connector to instrument cluster. Using ohmmeter, measure resistance between circuit tester terminals No. 3 and 10. If 40-50 ohms is present, leave all test equipment connected and go to next step. If 40-50 ohms is not present, repair open circuit to fuel gauge sending unit.
4. Connect voltmeter between circuit tester terminals No. 10 and instrument cluster fuel gauge terminal. (Scheme 5) If less than 4.6 volts is present, replace fuel gauge. If 4.6 volts or more is present, replace instrument cluster printed circuit board.

Scheme 2

Scheme 3

Scheme 4

Scheme 5

Brake Fluid Level

Fill master cylinder fluid reservoir. Disconnect electrical connector from brake fluid level switch on reservoir. Using an ohmmeter, check resistance between connector terminals of switch. Continuity should not be present. Remove reservoir cap. Press down switch pin. Continuity should be present. Replace switch if it does not test as specified.

Coolant Level

Fill coolant reservoir. Disconnect electrical connector from coolant level switch on reservoir. Using an ohmmeter, check resistance between connector terminals of switch. If continuity is present, replace switch.

Coolant Temperature (With Auto-Check)

1. Disconnect 4-wire connector from electronic thermoswitch on cylinder head coolant flange. Connect jumper wire between ground and terminal "C" of electronic thermoswitch connector. (Scheme 1)
2. Start engine and let idle. If indicator does not flash on and off, check indicator bulb. If bulb is okay, check wiring. If bulb and wiring are okay, replace coolant overheat/brake warning light module on back of instrument cluster.

Oil Pressure

System uses 2 switches on left side of cylinder block, one with White housing and other with Brown housing. Disconnect wire from switch terminal. Connect ohmmeter between ground and switch terminal. On switch with White housing, there should be no continuity. On switch with Brown housing, there should be continuity. Replace switch if it does not test as specified.

Windshield Washer Fluid Level

Fill windshield washer fluid reservoir. Disconnect electrical connector from fluid level switch on reservoir. Using an ohmmeter, check resistance between connector terminals of switch. With reservoir full, continuity should not be present. With reservoir empty, continuity should be present. Replace switch if it does not test as specified.

OIL PRESSURE GAUGE TEST

1. Disconnect oil pressure sending unit wiring harness connector located on left side of cylinder block. Connect Gauge Tester (VW 1301) between connector terminal and ground. (Scheme 6)
2. Turn ignition on. Set gauge tester dial to specified setting. See OIL PRESSURE GAUGE TEST SPECIFICATIONS table. If oil pressure indicated by gauge does not match oil pressure specified in table, check wiring. If wiring is okay, replace oil pressure gauge.

OIL PRESSURE GAUGE TEST SPECIFICATIONS

Scheme 6

OIL TEMPERATURE GAUGE TEST

1. Disconnect wire terminal from oil temperature sensor, located on oil pump housing. Connect Gauge Tester (VW 1301) between wire terminal and ground. (Scheme 7)
2. Turn ignition on. Set gauge tester dial to specified setting. See OIL TEMPERATURE GAUGE TEST SPECIFICATIONS table. If oil temperature indicated by gauge does not match oil temperature specified in table, check wiring. If wiring is okay, replace oil temperature gauge.

OIL TEMPERATURE GAUGE TEST SPECIFICATIONS

Scheme 7

SPEEDOMETER TEST

1. Ensure all fuses are okay. Start engine. Using trip computer function switch, select average vehicle speed display to zero. Drive vehicle. While at average cruise speed, push and hold trip computer RESET button for more than 2 seconds. If instantaneous vehicle speed is displayed, replace speedometer. If instantaneous vehicle speed is not displayed, go to next step.
2. Turn ignition off. Remove instrument cluster. Disconnect both instrument cluster 26-pin wiring harness connectors. Inspect connector terminals for damage and repair as necessary.
3. Connect Red 26-pin connector to Circuit Tester (VAG 1598). Reconnect Green connector to instrument cluster. Place transmission in Neutral. Raise and support vehicle. Position voltmeter on A/C scale.
4. Turn ignition on. Rotate left front wheel. Check voltage between circuit tester terminals No. 8 and 14. If voltmeter reads 1.0-4.5 volts, go to next step. If voltmeter does not read 1.0-4.5 volts, replace VSS or repair open circuit.
5. Connect voltmeter negative lead to circuit tester terminal No. 14. Connect voltmeter positive lead to VSS terminal No. 2 on instrument cluster. (Scheme 8) Rotate left front wheel. If voltmeter reads 1.0-4.5 volts, replace speedometer. If voltmeter does not read 1.0-4.5 volts, replace instrument cluster printed circuit board.

Scheme 8

RPM SENSOR TEST

1. Turn ignition off. Remove instrument cluster. Disconnect Green instrument cluster 26-pin wiring harness connector. Inspect connector terminals for damage and repair as necessary.
2. Connect Green 26-pin connector to Circuit Tester (VAG 1598). Connect Green test lead of Tester (VW 1367) to terminal No. 12 of Green 26-pin connector. (Scheme 3) Start engine. Engine speed should be indicated on tester. If engine speed is not indicated, repair open circuit in wiring harness.

TACHOMETER TEST

1. Turn ignition off. Remove instrument cluster. Disconnect both instrument cluster 26-pin wiring harness connectors. Inspect connector terminals for damage and repair as necessary.
2. Connect Green 26-pin connector to Circuit Tester (VAG 1598). Connect Engine Tester (VW 1367) to measure engine speed. Connect Green lead of engine tester to test pin No. 12 of circuit tester. Start engine. If engine speed is displayed on engine tester, go to next step. If engine speed is not displayed on engine tester, repair open circuit in wiring harness.
3. Turn ignition off. Remove circuit tester from Green 26-pin connector. Remove rear instrument cluster cover. Connect Green 26-pin connector to circuit tester. Connect ohmmeter between terminals No. 1 and 2 and then between terminals No. 3 and 4. (Scheme 9) If no continuity is present, replace tachometer. If 250-350 ohms are present, replace instrument cluster printed circuit board.

Scheme 9

VEHICLE SPEED SENSOR (VSS) TEST

1. Turn ignition off. Remove instrument cluster. Disconnect Red instrument cluster 26-pin wiring harness connector. Inspect connector terminals for damage and repair as necessary.
2. Connect Red 26-pin connector to Circuit Tester (VAG 1598). Place transmission in Neutral. Raise and support vehicle. Position voltmeter on A/C scale.
3. Turn ignition on. Rotate left front wheel. Measure voltage between test pins No. 8 and 14. Voltmeter should read 1.0-4.5 volts. If voltmeter does not read 1.0-4.5 volts, replace VSS or repair open circuit.

VOLTAGE REGULATOR TEST

Note. Ensure battery is fully charged before proceeding.

1. Turn ignition on. Connect voltmeter positive lead to voltage regulator terminals No. 1 and negative lead to voltage regulator terminals No. 2. (Scheme 10) Turn ignition on. If battery voltage is not present, check for open circuit in wiring harness and repair as necessary. If battery voltage is present, go to next step.
2. Connect voltmeter positive lead to voltage regulator terminals No. 3 and negative lead to voltage regulator terminals No. 2. With ignition on, voltage should be 9.75-10.25 volts. If voltage is not correct, replace instrument cluster printed circuit board.

Scheme 10

REMOVAL & INSTALLATION

CENTER CONSOLE

1. Disconnect negative battery cable. Remove ashtray. Unclip trim plate from rear half of center console and remove screws. Lift rear half of center console upward and forward off of parking brake lever.
2. Unscrew shift lever knob. Remove screws securing front half of console to floor and pull console rearward. To install, reverse removal procedure.

INSTRUMENT CLUSTER

1. Obtain radio security code. Disconnect negative battery cable. Remove steering wheel. Insert screwdriver into hole in bottom of steering column cover and loosen clamp on steering column switch. Pull steering column switch forward and disconnect electrical connectors.
2. Remove steering column switches. Remove instrument cluster screws and tilt cluster backward. Disconnect all electrical connectors. Remove instrument cluster. To install, reverse removal procedure. Recode radio. Tighten steering wheel center nut to 30 ft. lbs. (41 N.m).

Instrument Panel Wiring Diagram. Scheme 11

See also:
• AIR BAG RESTRAINT SYSTEM
• VOLTAGE REGULATOR TEST