Rev counter and econometer totaly dead

Tue Jan 17, 2012 8:56 pm

Hi there , i think got some problems with cables , rpm meter and econometer not working , fuel gauge always staying at 40 liters(but i can guess where is the problem ) , mp/h and temp working.(i checked with working one , same problems got to be from cables ) Started looking for some problems with the cables and find this out , someone knows what are these cables for ? i think 1 jack is missing in white one doesnt go anything ?? or maybe someone before me played with the car ? car is 318i touring m40b18 dec 12.1993 got clima and abs here is the pic (sorry for bad english)

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Tue Jan 17, 2012 11:20 pm

Sorry, can't make anything out on that pic!
There are four sockets on the back of an E30 cluster. White and blue are always connected, and many things won't work if either is disconnected. Yellow is only used in conjunction with an OBC, and the green (frame not always fitted) is mainly to supply a road speed signal to things like cruise control and radio volume.

Tue Jan 17, 2012 11:56 pm

i got all these sockets connected but the rpm and economy gauge still not working , car is left hand drive , picture is from the right side with removed glove box , these cables are somehow connected to the ecu

Wed Jan 18, 2012 12:16 am

ECU plug is part of the engine loom, and all connections to the instrument cluster are part of the body looms. Early E30s had a 3 pin plug and socket connecting directly between the cluster and the engine loom, but this was deleted years before your car was built.
The plug hanging off the engine loom is unused on most E30s, but yours will have a connection as part of the climate control.
Are the service LEDs working correctly? Dud batteries on the SI board can affect some of the instruments.

Wed Jan 18, 2012 12:55 am

After some reading around the net, the black which is with white is for air conditioning and and the white one is connector c104 ? for tach and fuel economy gauge ?, however, cannot find a jack for this white socket BUT there is signal on the 2 of the 3 pins who are inside , dashboard of the car is removed, there is also pins on the Motronic for tachometer and economy gauge (6 and 32) to (7 and 11), on c1 the blue connector for instrument cluster i got signals on these pins too but on instrument cluster tacho and economy gauge still not working.I called a friend with touring same like mine 318i m40b18 his instrument cluster is working ok , but on mine car is not working. There are two pins on the Motronic 47 and 48 (black and yellow) are for Pulse (Engine Speed) Crank Ref Sensor (+) and Pulse (Engine Speed) Crank Ref Sensor (-) some idea for what is this sensor? or how to check if it works? Could be from him ? Any idea where else can be the problem ? All The fuses are ok , batteries on the instrument cluster new ! please help

here is link for the c101 and c104 idk is it usefull or not :
http://webcache.googleusercontent.com/s ... clnk&gl=bg

Fri Jan 20, 2012 2:16 am

help !

Fri Jan 20, 2012 7:25 am

Do you have a spare rev counter?? If so try swapping it over and see what happens, its only held in with screws should just pull out of the cluster.

Fri Jan 20, 2012 9:12 am

A '93 car shouldn't have a C104. This is a relic of the early rectangular 'C101', although it survived long after the round C101 was introduced, up to around the facelift change over.
The wires that went through the C104 were then incorporated into spare pins on the C101.

Tue Jan 31, 2012 5:46 pm

problem solved , there was no supply on pin2 , blue socket (c1) , but there is supply on the fuse(21) for this pin , so maybe some problem on the cable , just wired new cable and all works correct now !