Need help with speedo wiring

[KevanP]

Need help with the wiring on my speedo. A wire has come off stopping the speedo from working.

The brown wire has come loose and not sure where it came from.
The loose red wire came from the new spade terminal which was in the position shown in the pic but came apart when I pulled it. So dodgy crimping. 
I'm thinking the brown wire was connected to the same place.

These are all on the speedo side and not the loom side.

[Dave Eastwood (Gadgetman) - Club Chairman]

Dodgy wiring indeed!

 

Soldered wires and plastic all in one crimps, a hateful combination, almost guaranteed to give trouble eventually.

 

Without knowing what the speedo that’s been swapped in is, it’s hard to be precise on what wires go where, however I can tell you what the loom side wires are, which may help?

 

Black - chassis ground

Green - ignition live to speedo

Yellow/green - signal back from speed sensor

Yellow/White - 12 Volt ignition live feed to speed sensor

 

red/orange - dash illumination

black (small gauge wire) - ground for dash illumination.

 

It’s hard to tell for sure from the photo, but it looks like one of the two loose wires should have been speedo signal, and the other speedo power. It may be that someone has reversed the power and signal connections at the sensor end, or it may just be a sender that doesn’t care which is which. 

 

Knowing what the speedo is and a copy of its wiring diagram would help enormously.

[KevanP]

Hi Dave, the speedo is the standard one from Westfield, it's on a 2014 SEIW. The red wire with the soldered end was in the spade terminal which is half pushed back into where it came from. It's the thin brown wire which comes from the speedo that I don't know where it goes too. I can only guess it was in with the soldered red wire as that's the only crimped spade that the red wire was loose in. The other two crimped spades were nice and tight, crimped properly. 

[KevanP]

Hi Dave, so have had a bit more of the dig around. The Speedo is an ESB instruments one, 80mm with rubber button on the glass front.

This is what I have wiring wise:

 

Loom (into plastic connector) - Function    Speedo Wires        Small 3 wire loom (I assume this is from the speed sensor?) They are very skinny wires

Black (Chassis GND)                                        Black

Green (Ign Live to Speedo)                               Red

                                                                              Green (not connected anywhere) but never looked like it was as the cables haven't been stripped - cleanly cut.

Yellow/White (12v ign. live to spd sens)        Yellow                    Black

Yellow/Green Speedo Signal (routes into a terminal block but nothing coming out the other side)

                                                                                                              Blue routes to Tacho instrument bulb

                                                                                                              Brown (this is the one in question - where does it go?)

[Dave Eastwood (Gadgetman) - Club Chairman]

Am I right, you’ve got black, blue and brown from the speedo sensor?

 

One with be 12 Volt power, one signal and one ground, normally.

 

On the ETB speedo instruction sheet - downloadable here

 

Black - signal

Brown - 12 Volts

Blue - ground

 

So,

Black connects to yellow green in the loom

Brown to either yellow white, or to green

blue to black

 

note however, that someone could have easily swapped  the yellow/green or yellow/white connections over at the sensor end, as long as black gets to a signal and brown to 12 Volts it would work.

 

 

[KevanP]

Yes Black, Blue & Brown from a separate little loom (cable tied to the main loom) - not sure where it goes, but it routes down to where the relays/fuses are on top of the transmission tunnel under the dashboard in the same location as where the loom runs through a gromit in the tunnel. So without ripping that lot out, I'm guessing its likely to go to the gearbox and would be logical to me to be the speed sensor wiring.

 

So from what you've said the brown from the small loom is the 12v live, which was the one that came loose. Plus the Red going into the main connector block was also loose, so this ties up that this is the 12v live. I'll put a meter on it just to check.

 

But thanks for your help 🙂

 

[Dave Eastwood (Gadgetman) - Club Chairman]

On most Westfield SEi’s from the late 90’s or so onwards, the speed sensor has been in one of two positions;

 

The off-side rear, where it’s mounted on the diff cage, and points at the bolt heads on the inner lobbro joint, which it effectively “counts”. Or from mid to late 2000’s or so, it’s on the front off-side upright, where it “reads” the heads of the four bolts that hold the brake disc on.

 

On live axle cars, they typically were in the transmission tunnel at first, reading the prop shaft bolts where it bolted to the diff. 

 

Note on some cars, owners just fitted them near drive shafts, and used magnets as targets, glued around the shaft.

 

Actually connecting to the speedo drive on the gearbox does happen, but is incredibly rare. As far as I know, the factory stopped doing it, when they changed from mechanical to electronic speedos.