Friday, 17 December 2021

BMW E30 / E28 Diagnostic Plug / Socket Pin Out Diagram

11.5BrownGround Distribution G101
40.5Brown / VioletGauges / Warning Indicators,
Coolant Temperature Sender
50.5White / GreenFuel Control,
Injector Control Module (Fuel Rate)
70.5White / BlueService Indicator,
Service Interval Processor (Reset)
112.5Black / YellowStart, Start Signal
120.75BlueCharge System, Alternator,
130.75BlackIgnition, Ignition Coil
142.5RedCharge System, Alternator
151.5Green / YellowIdle Speed Control,
Idle Speed Control Unit

BMW E30 Fuse Box Layout + Diagram


17.5AHeadlights (also 2, 13, 16)
27.5AHeadlights (also 1, 13, 16)
315AAuxiliary Fan (also 18)
415ALights: Turn/Hazard (also 24)
525AWiper / Washer
825ALights: Dash, Rear Defogger, 
Seatbelt Warning (also 10), 
Speedometer / Indicators (also 12)
915AIdle Speed Control / Vacuum Advance,
Reverse Lights
107.5ASeatbelt Warning (also 8), 
Service Indicator (also 24), 
Tachometer / Fuel Economy Gauge (also 24), 
Gauges / Indicators, Brake Warning system,
1115AFuel Delivery
127.5ARadio (also 21), 
Speedometer / Indicators (also 8)
137.5AHeadlights (also 1, 2, 14)
147.5AHeadlights (also 1, 2, 13)
15-Not used
16-Not used
1715AAccessory Connector
1830AAuxiliary Fan (also 3, 19)
197.5AAuxiliary Fan (also 3, 18), 
Interior Lights (also 21, 22, 27), 
Power Mirrors
2030AHeater / Air Conditioning (also 28)
217.5AAuto-Charging Flashlight, Digital Clock, 
Glove Box Light, Ignition Key Warning,
Interior Lights (also 14, 22, 27),
Radio (also 12), Trunk Light
227.5AInterior Lights (also 19, 21, 27),
Lights: Front Park/Tail, 
Front Side Marker
237.5ALights: Dash, Front Park/Tail, 
Front Side Marker, 
Rear Marker / License Plate
2415ALights: Turn/Hazard Warning (also 4), 
Tachometer / Fuel Economy Gauges (also 10), 
Service Indicator (also 10)
2525ANot used
2625ANot used
2725AInterior Lights (also 19, 21, 22),
Central Locking
2825ACigar Lighter, Power Antenna
297.5AFog Lights
307.5AFog Lights

Thursday, 9 December 2021

E30 Speedometer Schematic / Wiring Diagram / Pinouts

 ** For E30 speedometer / odometer troubleshooting and repair guide see THIS POST. **

The arrangement is the same with both VDO and Motometer type gauges. 

Pins are: 

R - 12v +

31 - Ground

31b - Speed sensor INPUT Pin 1

A - Speed sensor Pin 2 *NOT USED*

Bench testing can be achieved by powering the unit with 12v and simulating the pulse of the speed sensor over the two remaining pins, either way around. This is essentially done by creating a pulse across the circuit of pin A and A1. You can do this by just bridging the two pins together with a piece of wire and touching the wire against one of the pins on and off to make the ‘pulse’, as this is basically how the speed sensor works, but simulate any kind of actual road speed you will need to be doing the on/off pretty quickly. A far better way to bench test is to use some kind of ‘pulse-generator’, such as an oscilloscope or something set up using an Arduino, which is what I used to create a pulse with 5 volts. I will post a guide soon.

E30: Rebuilt and refitted instrument binnacle w/ new speedo/odo + more

  • Replaced speedometer / odometer.
  • Replaced back-light bulbs.
  • Checked and tested Si batteries.
  • Tightened brass-nut on temperature-gauge.
  • Bench-tested.

Sunday, 24 October 2021

E30/E28: Faulty AFM (Air Flow Meter) repairs, worn carbon-track quick fix


The AFM or Air Flow Meter uses a metal flap that is opened air entering the engine to move a brass arm up and down a carbon-track. The position of the arm along the carbon track alters the electrical resistance through the circuit and this lets the ECU know how much air is coming in, so it can deliver the right amount of fuel to the injectors. The E30 uses a BOSCH AFM unit, also used in many other BMWs with Motronic or Jetronic injection systems.

The analog electrics in the BOSCH AFMs rarely ever fail, but there are two areas that are failure prone after higher mileage - a worn carbon track and a faulty air-temperature sensor.

Saturday, 23 October 2021

E46 318i Touring: New front drop-link for MOT

The 318i Touring was up for MOT this week and failed only on the O/S front anti roll-bar link. Normally I would replace these as a pair, which would have been more cost effective as you can get a set of two from eBay for under £15. Time was an issue and I wanted to get it back for a re-test so had to buy one from Euro Car Parts for the same price, around £15. Annoyingly, the eBay pair were Lemforder and the single piece from ECP is Starline, but needs must.

The car has only just passed 104k miles, so this could well have been the original anti-roll bar linkage and boy was it seized on. I only got a couple of turns on the top nut before the 5mm Allen-key in the stud stripped and rounded, so had to cut the rubber boot off to get a 17mm spanner on to the flats at the back. Even so, progress was painstakingly slow. Couldn’t even get a grinder in there as things are surprisingly tightly packed on E46. This made an otherwise quick and easy job last a bit longer, but it is nearly 20 years old.