tachometer fault

[BMW_E30vert]

Im re-commissioning a cab that's been of the road for 4/5 years the problem i have is only my temp gauge is working on the tach, no rev, speedo or fuel gauge are working, ive tried a known working cluster but its the same. the low level fuel light doesnt come on when the ignition is on but when i bridge wires on fuel sender it turns on but needle doesnt move.
car is a early 325i 86 with a external pump and just one fuel sender unit under the seat. some monkey has had a play with the wires behind glove box, would be helpful if i could get help identifying the wires which supply tach with info or any wires in particular i should look out for.

Osman

[Grrrmachine]

Wiiiiikiiiiii

http://www.e30zone.net/e30zonewiki/inde ... Tachometer

http://www.e30zone.net/e30zonewiki/inde ... g_Diagrams

[BMW_E30vert]

have read through the wiki but cant pin point the problem need some help are there any wires behind glovebox which could cause the problems?

[Brianmoooore]

There's no low fuel light 'test' function on an E30 when the ignition is turned on, like on later models. If the light comes on when you short the wires at the sender plug, but not when connected to the tank sender when the tank is empty, then the sender is faulty. (Gummed up from evaporated fuel?)
What happens when you short the fuel gauge wire to earth at the sender plug?
Tacho wire will be the plain black one in the three pin plug and socket referred to in the wiki, if your car is '86.
All the other wires to the instrument cluster (including the tacho wire on later cars) pass behind the glovebox area, but there are (should be!) no joins or plug/sockets in them.
Better wiring diagrams here: http://www.autolib.diakom.ru/CAR/BMW/ , but only has the later version, where the three pin plug wires run through the main engine loom plug. Actual circuit is the same.

[BMW_E30vert]

thanks Brian, when i short the wires in the sender plug only the low fuel light comes on needle does not move

[Brianmoooore]

Shorting brown to brown/grey should put the light on, and shorting brown to brown/green should move the fuel gauge to full.
If the former happens, but not the latter, there's either a break in the brown/green wire, or the instrument cluster is faulty.

[BMW_E30vert]

i believe there is a wiring problem there are some wires behind the glovebox that look lost (il post pics). when i got the car the dash was removed ive put the dash back in and a known working tach but only temp gauge works tach doesnt even light up

[Brianmoooore]

The two wires I've mentioned above go to the front of the car via the LH sill, and come up behind the glovebox underneath the front of the speaker trim panel. They are then part of one of the two looms that go across behind the dash.
One of these looms unplugs in the LH corner behind the glovebox, but the one in question is continuous with no plugs and sockets.

[BMW_E30vert]

pic 1
these wires are all together and are cut but cant find what they possible connect to


pic 2
there is no plug on this and cant find anything to plug into this



pic 3
these are two green/green black wires which arent part of any loom just coming through the bulkhead glovebox side



pic 4
these are the relays behind glovebox



pic 5
there are also these wire coming of the thicker loom in this pic red/green and brown

[mcbonio]

Don't you just love having to undo previous owners awful bodges?