bmwrepairs: How to replace gauges on 2005 BMW 325?

Instrument cluster needs to be removed.

Gauges

Removal & Installation

E30 Models

Remove the instrument cluster.

Remove the 9 screws from the back of the cluster; 8 arranged around the perimeter and 1 in the center.

Pull the housing off the cluster.

Remove the gauge mounting screws and pull the gauge off.

Install the gauge and the mounting screws. Mount the housing on the cluster and affix the screws.

Install the cluster in the dashboard.

Testing

Engine Coolant Temperature Gauge

The engine coolant temperature gauge uses a heat sensitive variable resistance grounding circuit to monitor the engine's coolant temperature.

The coolant temperature information is conveyed to the instrument panel from the gauge temperature sending unit. To test the gauge and its related components, first test the gauge operation to make sure the problem is not in the gauge or gauge wiring. To test the gauge operation, perform the following procedures.

Gauges Using Single Wire Sensors

Check the fuses and replace as necessary.

With the ignition switch OFF , disconnect the electrical connector from the gauge sending unit.

On models with a single wire coolant sensor, connect the wire for the temperature sensor electrical connector to a known good chassis ground.

Turn the ignition switch to the ON position for a brief moment. The coolant temperature gauge should register as full hot.

If the gauge reads correctly, replace the sensor. If the gauge does not register, check for a damaged or shorted wire, electrical connector or a faulty gauge.

Gauges Using Two Or Four Wire Sensors

Check the fuses and replace as necessary.

With the ignition switch OFF , disconnect the electrical connector from the gauge sending unit.

On 1996-98 models with the 4-wire electrical connector, locate the electrical terminal positions 1 and 2 of the electrical connector (refer to the illustration provided). On E36 M44 models, the terminal position 1 is the brown wire with the violet tracer and terminal position 2 is the brown wire with the yellow tracer, however this may differ from year to year and model to model.

Obtain the listed resistors to achieve the following gauge results:

8,200-10,500 Ohms: Temperature gauge should read cold (12-16°F (-9-11°C))

2,200-2,700 Ohms: Temperature gauge should read slightly warm (66-70°F (19-21°C))

500-400 Ohms: Temperature gauge should read normal operating temperature (174-178°F (79-81°C))

300 Ohms: The gauge should read full hot.

CAUTION

Failure to correctly identify and probe the correct terminals of the four wire electrical connector may cause severe damage to the control unit or other electrical components.

Turn the ignition switch to the OFF position.

Connect one of the three resistors in series with two suitable electrical probes attached to terminal positions 1 and 2.

CAUTION

Do not force a test probe into an electrical connector. When using an electrical probe use care to not damage the connector. If an electrical connector is damaged it should be replaced.

Turn the ignition switch to the ON position for a brief moment and monitor the operation of the engine coolant gauge. The coolant temperature gauge should register as outlined above.

If the gauge reads correctly, replace the sensor. If the gauge does not register, check for a damaged or shorted wire, electrical connector or a faulty gauge.