Tacho not working

[Linden 0]

hey guys i recently brought a e30, 318i FL with a m20b25 manual, it was someones unfinished project, few things wrong with it like reverse lights not working (still got a warrant somehow), and needs thrust bearing replacing.

the thing thats bugging me right now is the tacho that doesnt work at all (also the fuel economy)

I have tried replacing the SI board batteries but that didnt work, ive looked around and havnt found to much else other than i may have to replace the guage itself.

it has the 2 plugs on the back and the yellow one is unused (im assuming this is for OBC which i dont have?)

If anyone has another suggestion before i replace the whole dash just to find out a wire wasnt connected someware or places i should check?

i also found this unused plug when poking under the dash just behind the glovebox (see pic)

Edited August 18, 2008 by Linden

[williams 0]

the tacho wire might be disconnected as the 4cyl and 6 cyl signal are different(pulses) most clusters have a coding plug which tells the tach if its a 4 or 6 cylinder start by checking if ur car has the original cluster?as for reverse lights theyre not a wof issue...what colour wires are in the relay holder?

[Linden 0]

the tacho wire might be disconnected as the 4cyl and 6 cyl signal are different(pulses) most clusters have a coding plug which tells the tach if its a 4 or 6 cylinder start by checking if ur car has the original cluster?as for reverse lights theyre not a wof issue...what colour wires are in the relay holder?

does the cluster have a code on it that i can use to check for 4/6 cyl ill have to pull it apart again and check, im assuming you're talking about the little white box that is plugged into the front. i have a parts car in dunedin but thats pre-FL so wont be much help will it?... probally sounds dumb but what relay holder are you talking about?

[williams 0]

if the other car was a 6 cyl then the cluster should work-not sure about the plug no's... the plug ur refering to is it the white connecter in the bottom of the dash?then that is the relay holder

[Linden 0]

I pulled out the dash again and the coding plug is from a 318i (m40) http://bmwfans.info/part-62111385364/ so looks like i'll need a 325i one so if anyone has a spare one they want to part with!

i pulled out the glove box and took a photo of the wires on the unused plug sitting there, all the green/yellow/white and the fatter yellow/red wire goto the plug (see pic)

[WAZZACSI 0]

hey guys i recently brought a e30, 318i FL with a m20b25 manual, it was someones unfinished project, few things wrong with it like reverse lights not working (still got a warrant somehow), and needs thrust bearing replacing.

the thing thats bugging me right now is the tacho that doesnt work at all (also the fuel economy)

I have tried replacing the SI board batteries but that didnt work, ive looked around and havnt found to much else other than i may have to replace the guage itself.

it has the 2 plugs on the back and the yellow one is unused (im assuming this is for OBC which i dont have?)

If anyone has another suggestion before i replace the whole dash just to find out a wire wasnt connected someware or places i should check?

i also found this unused plug when poking under the dash just behind the glovebox (see pic)

[WAZZACSI 0]

Try checking your fuses there ts one fuse in the main fusebox that will stop the tacho and economy gauge working, Cheers Wazza

[Linden 0]

Try checking your fuses there ts one fuse in the main fusebox that will stop the tacho and economy gauge working, Cheers Wazza

yup one of the first things i checked, fuse 21 i think it was for that.

[QuickSilver 0]

From the m20b25 MCU plug (the plug you pluh straight into the ECU) pin number #32 and #6 are what control the tacho and econo meter.

When I swapped from my L-jet setup I had a similar issue, but the problem was that the old L-jet actually ran a seperate plug for the tacho and econo meter, it had three wires, and it seperated from the main loom just before plugging into the ECU.

I connected #32 to the brown/yellow and #6 to the blue/black wire from the old plug that went into my dash, the third wire became obsolete and did nothing.

#32 is a white/black wire and #6 is a black wire.

I dont know if that helps, but there ya go.

Edit: I dont know if your's was motronic 1.1 or 1.3, but the above refers to motronic 1.3, I dont know about the other setup.

Edited August 26, 2008 by QuickSilver

[Linden 0]

i cant find the brown/yellow and blue/black wire you're talking about,

ive attached a pic of whats been done there already.

coming out of the MCU plug is:

unconnected white wire and black/blue.

light blue/yellow connected to brown/orange going into loom

- does anyone have a wiring diagram for the MCU plug so i know what these wires do?

also theres a green wire coming out of the loom connected a green wire (has unconnected purple and brown wires with it) that goes down under drivers kickboard

[QuickSilver 0]

I can't find my wiring diagram at the moment, so I can't tell you what those wires do, I will have a look, BUT to find the wires you need for your tacho, open the MCU plug so that you can see the back of it (easy) it just slips out, and count the pins on the front of the plug, find #6 and #32, they are both single wires (dont run into bigger bunches) Find them and mark them, so that atleast you can confirm that you have the tacho wires.

It looks like someone has played with this loom a bit before, those plugs you have there unconnected look as though they could have been used for an alarm at one stage,

Edit: that plug that you have there, is the same plug that I had in mine, and is the one I had to use to make the tacho work, the brown/yellow wire coming from it may be the same on? Try follow it back and see if it has been added into the main bundle and comes back out again further up?

Edit edit: Is the car motronic 1.1 or motronic 1.3?

Edited August 29, 2008 by QuickSilver

[Linden 0]

i'll have a closer look at the plugs tonight and find #6 and #32

i looked up the code on my motronic box and found its apparently a 3.3:

325i 2.5 litre (M20), 85-87

Bosch Motronic ML3.3

0 261 200 073

[QuickSilver 0]

Sorry that means you have a Motronic 1.1 setup, which means it has the sensors on the bellhousing, which means the wiring may be different and I dont know the setup, I cant check it for you as I dont have a 1.1 car handy,

[Linden 0]

gutted ill try ask on e30tech.com once my account gets activated.

in the mean time does anyone know if a 318 m40 coding plug will effect the tacho,

and possibly someone in chch have a working F/L dash cluster i could plug in and check if its not just my guage thats not working?

its getting frustrating not knowing where the problem lies but im determined to fix it lol.

edit: you said the sensors on the bellhousing, where abouts would i look to see if the sensors hooked up at all?

Edited August 30, 2008 by Linden

[QuickSilver 0]

Sensors are on the passenger side of the gearbox bell housing, if their not hooked up nothing will be working, so if your driving the car around the sensors are definately hooked up.