Instruments

Dash Cluster

The E30 was fitted with a multi-instrument binacle featuring all the standard clocks and dials expected of a car. A Speedometer, fuel guage and coolant temperature gauge were standard across the range, while all M20 models received a Tachometer (rev counter) and econometer as standard.

On the centre console, next to the stereo (if fitted) and above the heater controls, was the option of a Clock or an On-Board Computer (OBC). The OBC was available as a basic 6-button or an advanced 13-button instrument.

Above the rear view mirror of M20 models was a check panel, which warned the driver of any problems with lights and fluids.

Construction

The dash cluster is a one-piece circuit board inside a plastic shell, mounted to the dashboard. It receives its information through three plugs (white, blue and optional green) connected to the rear of the circuit board. The dash cluster is powered by Fuse 27.

To control a number of the instruments, batteries are fitted to the back of the circuit board. Many problems associated with the dash cluster are caused by failing or leaking batteries which need to be replaced. Learn more about replacing SI batteries

Inside each dash cluster is a coding plug, which is specific to each engine, be it a 4-cylinder or 6-cylinder unit. When replacing your dash cluster with that from a different model, it is an incorrect coding plug that causes instrument problems.

Learn more about replacing your Dash Cluster. Learn more about Changing your dials.

Speedometer

The speedometer takes its reading from a pulse generator in the differential. This is a very simple sensor and very rarely breaks; however the plug from the sensor is exposed to the road, and the wires very often corrode and break. If your speedo isn't working, cut off the plug and 30cm of wire from the differential sensor, and replace.

Temp Gauge

The E30 temperature gauge is not linear - it's compressed at each end, with the whole centre section, from just clear of the blue to just before the red, covering just a few degrees. The needle anywhere is this whole section is fine, according to BMW. In practice, E30's have the needle just past the 1/4 mark, or almost exactly on the centre mark, depending, presumably, on the thermostat fitted.

Tachometer

The tachometer is arguably the most problematic instrument in the dash cluster, and the source of 90% of dash problems. Most of these issues can be traced to the SI batteries.

However, on older vehicles (earlier than 1987) the simpler engine management system provided tachometer and fuel rate data through a separate plug, not the main loom. If your pre-facelift car has Tachometer issues, try to locate the small three pin plug and socket above the pedal area, and ensure that it is connected properly.

Dash Lights

Check Light

Some cars, specifically US and European models, were fitted with a CHECK light in the centre of the dash cluster. If a fault displayed on the check panel, then the CHECK light would flash to warn the driver of the fault. The CHECK light would stop flashing once the Check button was pressed on the check panel.

It is sometimes possible to check Motronic faults using the CHECK light. Learn more about Motronic fault codes.

Brake Lights

For those cars fitted with brake pad sensors, a flickering light is a known issue.

Inspection Lights

Main article: Resetting the Inspection lights.

If your Inspection lights constantly glow, even after being reset, this is usually a fault of the SI batteries.

OBC

Main article: 13-button OBC