no oil pressure light

the plug you mention is for front fogs, so dont worry about that.

just to be clear, switch on head = 0.3 bar, when triggered light should flash only, no oil buzzer. i.e. when you switch on the ignition

one on filter carrier = 1.8 bar, and when triggered both the light and buzzer will sound, but only if the rpm is over 1.8-2k. otherwise the light and buzzer would always on when idling hot as pressure is lower than 1 bar

the filter carrier switch should have a blue/black wire, head should be yellow. if its a later cabrio or scirocco the wire colours may be reversed, so double check that.

the fact that earthing the head wire still doesn't trigger the light would lead to a wire fault, dash fault or maybe the plug between the yellow wire and dash loom is disconnected. on earlier mk1 there is a spade connection on the yellow wire, later mk1 this wire is moved to the fusebox plugs and instead the oil temp wire is on a spade. so check behind the fusebox area for a yellow wire coming in with engine loom and be sure its plugged in

there is no fuse for the oil warning circuit its just fed off the same ignition live as all the other dash bits, so if the other stuff works ok its not the ignition feed at fault

Thanks John, great information as always.

I've got an 1983 GTi so presumably it should have a connection from the yellow wire to the dash loom behind the fuse box.

If it's not a break in the yellow wire somewhere presumably the next step is to pull the clocks and look at the connections there.

being an 83 it could be either, its about then they changed from what I can see with all the millions of looms i get in

have a look at the plug on the dash loom as you say, the pins can squish down with age so need a tweak to make good contact again, look at the solder pads on the socket too make sure those haven't come away. a top tip on here was remove socket then pack out the pcb foil with a bit of paper to help make better contact

hmm 3.3v at the oil pressure switch with it disconnected isn't looking great. Either the dash has blown up or it's still not earthing correctly. I still have the indicator light glowing dimly when the ignition is on, so I still suspect the latter.

I've cleaned up the crown connection by the fuse box, the main engine earth and the one to the head.

I've found and checked the connector with a white wire and a yellow wire under the dash - I assume that that is the oil pressure switch but need a helping hand to check the resistance!

Where behind the clocks do the connect to earth? Anywhere other than the multipin connector?

Also, where does the indicator circuit come into the instrument pack?

If you've got lights on the panel glowing dimly, then I suspect you don't have a proper earth to your instrument panel. The Earth cable for it is actually a brown cable with a white trace which normally connects to the rocker cover in the engine bay - this provides the best earth to allow accurate instrument readings. If this earth is not connected then your instruments could do all sorts of weird things so check this definitely.

Hi Maniac

Thanks for the answer. I agree I don't  think the panel is earthing correctly either. The brown and white earth to the rocker cover is definitely making a good connection at the engine end. What I was wondering was how it connects to the instrument panel. Is it just through the multipin connector to the flexi board or should there be other earth connections on the panel?

Cheers

Simon

I hapen to have a spare set of clocks downstairs, so here's a pic of the connector - they're all labelled.

Pin 2 is the earth (masse)

Pin 9 and Pin 11 are the 2 oil sensor inputs.

the dash earth is similar to the oil pressure wire you found, theres a spade connector near the fusebox where dash earth wire joins the engine loom earth. you might find that someone has tapped into this wire and screwed to the chassis somewhere so worth a look.

this list should help
T14 - main plug
1 - blu/gry - Lights on feed
2 - brn - Earth
3 - pur/blk - Fusebox pin B/3 (fuel level sender)
4 - blu/yel - Fusebox pin B/7 (coolant temp sensor)
5 - red/blk - Fusebox pin B/19 (rev counter)
6 - red - Fusebox pin B/12 (permanent live)
7 - blu/wht - Fusebox pin A/28 (high beam warning)
8 - brn/wht - MFA switch mode button
9 - yel - Fusebox pin A/4 (high oil pressure warning switch) (blk/blu on early models)
10- brn/red
11- blu/blk - low oil pressure warning warning switch (yel on early models)
12- blu - Fusebox pin A/16 (alternator warning light)
13- blu/red - Fusebox pin A/17 (indicator warning lamp)
14- blk - Fusebox pin A/8 (ignition live feed)

T6 - back of the speedo
1 - wht/blu - outside air temp sensor
2 - wht/red - outside air temp sensor
3 - grn/blk - Fusebox pin B/15 (oil temp sensor)
4 - blk/yel - Fusebox pin A/3 (Gearshift control relay pin 3/L)
5 - wht/grn - Fusebox pin B/18 (Gearshift control relay pin 5/G)
6 - yel/wht - speedo sensor output

T2b - back of clocks, rev counter side
blk/wht - MFA switch memory button
red/wht - MFA switch reset button

After a good go at it over the last week or so I am sure that the oil pressure circuit on the board is not working. Time to look out for a set of clocks to cannibalise unless someone has the circuit diagram for it?

Cheers

Simon

BTW just for interest, it looks like the poor earth of the dash through the indicators is actually the other way around, it the indicator flasher unit seems to be earthing through the dash, and is an incorrect ford one.

New one on the way!

S

Sorry for bringing up this old post. 
I dont have oil lamp when i turn ignition on, but i have a loose yellow spade wire in the back of my fuse box. 
Anyone know where it goes?

flipp_76 said

Sorry for bringing up this old post. 
I dont have oil lamp when i turn ignition on, but i have a loose yellow spade wire in the back of my fuse box. 
Anyone know where it goes?

Knowing the year and Model of your ride goes a long way to getting the proper fix in the proper time…

It's a 81, 1.5

for an 81 you should have a blue/black wire to the white pressure switch in the oil filter housing, and usually there is no 0.3 bar switch in the side of the head with yellow wire which means you wont have an oil light with ignition on

if you do have a blue or brown switch in the side of the head with a yellow wire then the spade you found is probably on the other end of this wire, and plugs into a mating connector in the dash harness which then goes to the clocks pin 11

Found the mating connector. 
Thanks robjonny

good stuff