1993 K series 1400 Supersport Oil pressure sender connections

[Toby S]

 Hi All

Over the weekend, my oil pressure gauge, which typically fluctuated between 1.5 bar to 4.5 started jumping all over the place up to 9 down to 2. Given its an electronic version (yes I know they are problematic), I thought I'd investigate.

It had 2 connection on the top of the sender, one connection going into the loom or sub loom and the other was just a dangling wire with a spade connector (female end) not attached to anything. I took the sender off and cleaned up the connections etc and refitted, but couldn't find where the loose wire was supposed be connecting to - the 1993 handbook wiring diagram, doesn't give much of a clue I'm afraid.

Started up the engine and the gauge was reading and more steady only the pressure readings were down (the bad news), although the fluctuations were back to a normal 2 - 2.5 bar (not so bad news) on revving, only the max reading was circa 3.25 bar and then around 1 bar at the lower end. 

I'm always a bit nervous with dangling wires and low oil pressure - Does anyone have any idea where what the other terminal is supposed to connecting to.

I would guess it will be similar connections for any of the K series electronic senders if anyone could have a look

Cheers

[Wrightpayne]

What colour wire is the dangling one? There is an apollo temp sender wire spare in the vicinity (usually wrapped around the chassis tube if not in use)

As you’ve probably researched the electric senders have a tendency to go dolally - get a mechanical oil pressure gauge. There is lots in the archives.

 

[Toby S]

Cheer WP

I think it was blue (might of been black/brown) - I'll have a look tomorrow, but it was hanging off the sender, as opposed to hanging off a loom, hence the query

Would an apollo temp sender wire connect off the pressure sender ?

 

[Wrightpayne]

No - the apollo has a threaded boss which takes a standard K series water temp sender. The other end of the wire surfaces behind the dash - using an indicator type switch wired with the water temp gauge you can toggle between water and oil temp on the one gauge.

 

[Toby S]

Won't be that then as it was the wire was hanging off the second terminal on the oil pressure sender that was dangling - both connections on the sender are by screw down nuts and 'O' ring electrical connectors on the wires, with like I say a female spade connector on the other end of the dangling wire 

Do other people have 2 terminals on their sender I guess is the next question, if so where do the wires go coming of the sender lead to.

[SLR No.77]

IIRC the 1400 Supersport OP sender was able to provide the signal for the gauge and also had a switch built in for a low pressure warning light, I suspect this is your second terminal and wire. The race cars had a big warning light in the middle of the dash which was fed from the sender, I think the warning light had a +ve feed and the earth was provided by the sender until suitable OP was established, at which point the light went out.

It can be tested ... check for continuity between the cable and earth without the engine running and again with the engine running ... this will tell you if it's an earth for the warning light. My memory's a little shoddy on this though!

Stu.

[TomB]

Stu has a good memory! My 1996 1.4k had a twin contact sender, with one wire for the gauge and one for the warning light.  these were attached using two plastic screw on knobs.  Once one fell off as I was driving and the gauge was jumping around all over the place.  It didn't half make me panic.  If you want to know and can wait until this evening I can let you know wiring colours as currently it s all in pieces and very accessible to check. 

[Toby S]

Thanks Stu

Hi Tom

Same screw knobs on mine too - its a VDO sender unit

That would be great if you could have a look - it's really knowing where the 2 wires from the sender are connecting to - One (which I think must be the gauge given I'm getting a reading) is going to a loom just by the cambelt cover in front of the sump and is connected, the second (I can't find a position for but there doesn't seem to be a place in same loom though which seems odd) and I can't see where it's meant to go.

Re the red warning light on the dash - that seems to be working as on start up it does stay on for around 2 seconds and then goes out on a blip of the throttle  - can't see how it's oil pressure related if the there's no wire going to it, although I guess its also a warning light for the alternator producing sufficient charge

I hate electrics me

Cheers

 

[Jonathan Kay]

Great advice above. Could you add a photo to the wire colours?

...

... the 1993 handbook wiring diagram, doesn't give much of a clue I'm afraid.

The early diagrams for Ks that I have show an oil warning light switch: main loom, item 21, BY wire. Does yours have that?

Re the red warning light on the dash - that seems to be working as on start up it does stay on for around 2 seconds and then goes out on a blip of the throttle  - can't see how it's oil pressure related if the there's no wire going to it, although I guess its also a warning light for the alternator producing sufficient charge

The oil pressure warning light should have two wires: BY and G, item 23 in the diagram.

Jonathan

[SLR No.77]

Toby, your red light on the dash which is going out is for the charging circuit and nothing to do with oil pressure.

The light I referred to in the "middle of the dash" is a large diameter yellow lamp positioned just below the two tonneau poppers on the scuttle, if your car was not supplied as a race car it will not have this light included unless someone has added it themselves.

During the few years that the 1400K engine was used, ie. prior to the introduction of the 1600/1800 in '96, there was a race series for standard "sealed engine" Supersport cars, these cars were supplied with LSD, 4-1 exhaust, FIA bar and 13" wheels shod with Yoko 21R tyres therefore were a good price/specification to be used as a road and occasional trackday car. Many were bought with no intention of racing. It might be that your car was supplied as one of these, it might be that all the 1400's have the second connection on the OP sender.

Stu.

[Toby S]

Thanks Stu

My car ain't got the yellow light,but has all other other bits you mentioned (LSD, 4-1 Exhaust, FIA roll bar, 13" wheels (although now shod in R888R's) - it originated as a Silverstone track day car,  back in the early 1990's  I know that although was re-engined in 1999

Might explain the none connected wire though given no yellow light

I'll see if Tom can come through with any thing if he has a chance to look at his and I'll try and take some pictures this evening as JT suggests

I'm also hoping to go on the Fish 'n' chip run Saturday so if I can't get anywhere in the meantime I may wander around the car park asking any K series people to lift the bonnet so I can have a peek !!

 

 

 

 

 

 

[SLR No.77]

Your sender type is only applicable to the 1400’s which had VDO gauges, the changes in ‘96 were substantial including Caterham branded Caerbont gauges with Caerbont senders so only one wire after ‘96.

Stu.

[TomB]

Hi, I’ve had a look in the garage. A photo won’t help as my wiring isn’t original at the oil sender. But I’ve got two connections:

1) out of the part of the wiring loom that has the alternator plug on it, it’s a brown & white wire.

2) out of the part of the loom that is for the LHS headlight, it’s a black & yellow wire. 

In both of the above I’ve attached new wires with connectors to join the sender. I can’t remember why I did that but the wires emerging from the loom should be original colour.

i hope that helps. 

[Jonathan Kay]

1) out of the part of the wiring loom that has the alternator plug on it, it’s a brown & white wire.

I don't have a diagram of the engine loom. But are you sure that isn't White/Brown? That's "standard" for "Oil pressure switch to warning light or gauge; or starter relay to oil pressure switch".

2) out of the part of the loom that is for the LHS headlight, it’s a black & yellow wire. 

See #9 above.

 

Jonathan

[TomB]

White/ brown, brown/ white! One or the other! 

[Englishmaninwales]

Looking at the 1400 oil pressure sender/ loom/ filter housing on my car (now 1800) is a VDU sender with a single post terminal. The sender wire is white/ red. The sender take off is fitted above the filter housing.

No second wire.

The sender is available from Mardi Gras Motorsports, but expensive (around £50 - 60 about 5 years ago).

Malcolm