water / oil temp gauge switch mod - advice needed

[tomwood]

Hi all,

I've had a trawl of the archives but am still a little unsure what I need to wire up to where.

im trying to wire in a switch so I can flick between water / oil temp utilising the existing coolant temp gauge. I have the caerbont standard caterham gauge as fitted to a 2013 car.

the back of the gauge looks like this:

Having looked at the manual for this type of gauge, my interpretation is (when looking at the gauge from behind) that the (L) terminal = temp sender (2x green/blue), Middle = ground (2x black) ® = power (2 x green)

first Q, am I right in my assumption?

second Q, why are there 2 wires going to each terminal, I would have expected just 3 wires total, Instead I appear to have 6?

I've bought one of these switches from Caterham:

If I've understood correctly am I right in thinking I need an oil temp sender wire to the left most terminal, water temp sender to the right most terminal and then a wire from the centre terminal into the back of the gauge?

if so then the bit im unsure on is which of the wires currently feeding into the back of the gauge is actually the current water temp sender that I need to cut?

thanks,

Tom

[sjl1]

Hi Tom

Reading your post it all looks good, dont know why wires are doubled up, perhaps earth and lamp wires are stringing along all the instruments. No need to cut feeder wire, just carefully prise it out of socket and plug into switch and prepare short lead from switch into gauge plug using spade terminals (ebay is your friend)

im guessing sender wire is single green blue but its easy to work out with a multlimeter

Make sure switch is lined up horizontally with indicator switch and exactly between oil and water gauges.

I do like this mod, its cheap and effective

Enjoy

Simon

[ScottR400D]

I did this mod, it works well but I didn’t go anywhere near the gauge. 

Disconnect the water temp sender lead at the submarine. Make a lead that connects to that lead, run it to common on two way switch. 

Make a lead to go from water sender to switched terminal on switch. 

Make a lead to go from oil sender to other switched terminal

Easily reversed if necessary but works really well and is simple to do.  

 

[Jonathan Kay]

Are there two or three pictures in #1? I can see two plus an error icon.

What Simon says.

Power and earth (and power to instrument lights) are probably daisychained... it can be easier to wire that way than as a fan.

Let's confirm the colour of the signal wire from a diagram: have you got the appropriate one for your 7? Let me know if not.

What's the specification (or declared purpose) of the switch? Do you want to hold it to read the oil temperature then spring load itself back to water, or to sit by itself either way?

Do you know that your sender for the oil temperature matches your sender for the water temperature?

Jonathan

[ScottR400D]

Btw I replaced the original sender with the same thing but with a threaded male connection so that I could use a ring connector instead of the OE bodge idea. 

I got an identical one for the DS tank. 

I can find the supplier and have images if you're interested. 

[sjl1]

The 1/8 npt bog standard caterham water temp sender is the one to go for, have used this on k-series, sigma and now duratec and it works well, sigma oil temp gets quite high on the gauge ~110c but duratec seems to run a lot cooler ~80/90c

​sending a single wire from your oil temp sender around the chassis and up past the bell housing and through the grommet with the main wiring loom into the scuttle is the best route, then switch between water and oil feeds at the gauge end as originally suggested. Useful mod for seeing how hot oil gets on track days

[ScottR400D]

This was the sender I got two of, from ebay:

1/8 NPT Oil/Water TEMPERATURE TEMP Sender Sensor fits Autometer VDO Smiths Gauge

I do have images but I'm struggling to upload. Have things changed?

 

[tomwood]

Simon - Thanks for confirming, I'll have a go at removing the relevant terminal out of the back of the connector and see how I get on, failing that I could indeed do as Scott suggests and run another wire to where the submarine pipe is and make that a (very) long feeder wire into the gauge. I guess I'd like to try and avoid doing that If I can though as I've now put the tunnel back on and covered over the grommet where all the wires feed through.

I will indeed measure carefully to make sure I cut a hole for the switch in the correct place between the dials etc.

@Johnathan - Not sure why the images aren't working for you. There are 2 in my OP that should be rendering, I uploaded them to the club server I think so should work fine for you so not sure whats happening there. To answer your question, the car is a 2013 SuperSport R and no, I don't have the wiring diagram with colours etc unfortunately. The switch that I have bought is from Caterham. I believe its the same one that's used for the dip/main beams for headlights and as such is an on/on switch with no off position in the middle like the one for the indicators. As for the specification for the senders, I'm just going to have to find out by trial and error I think. the sender in the submarine pipe came with my Kit from Caterham. Likewise, the sender that is in the dry sump was put in by Caterham when they did the dry sump conversion for me so I'm just hoping they are the same spec.

@Scott - Should my hunch prove incorrect, a link to where you bought the appropriate senders from would be great. Presumably they are the correct resistance ones so that the gauge reads correctly? Have you done any independent testing with an IR gun or similar to make sure your getting an accurate result on the dial still?

Thanks for the help guys, much obliged.

Tom

[tomwood]

@Scott, thanks, I can see those on ebay, I'll bear that in mind if the ones i've got don't work as expected.

@Simon, those are the senders I'm pretty sure I've got and I have done exactly as you describe and already put in the wiring from the dry sump to the back of the dash so it's just wiring up the switch that's left to do now.

Tom

 

 

[ScottR400D]

Yes, the new senders give the same readings as the old and check out against an IR pyrometer. They’re the same spec so that’s to be expected. 

I still prefer my method to going in at the gauge. The ‘lengthened’ water sender cable is no longer than the new oil one and the whole thing is reversible in minutes, if necessary.

I’ll get links and images later. Also details of the switch I used. It has a waterproof cover and fits very neatly. 

[Jonathan Kay]

Not sure why the images aren't working... 

I can see two OK, but there's also a little blue error icon:

Jonathan

 

[Jonathan Kay]

To answer your question, the car is a 2013 SuperSport R and no, I don't have the wiring diagram with colours etc unfortunately.

If you'd like one please send me a Private Mail with your email address.

Jonathan

[ScottR400D]

[ScottR400D]

[ScottR400D]

Sorry about the images, they're the best I can do. I really struggle with putting images on here, no trouble on other sites. It just seems very complicated and inconsistent.

 

Anyway, hopefully, you can see the connections at the water sender, the way the wires were wrapped and put through the bulkhead, and the switch I chose. I put it between the oil and water gauges, it shows the temperature of whichever gauge its pointing at.

I got the senders from ebay, the supplier doesnt seem to have any now but others do, search on

'Oil Water Temperature Temp 1/8 NPT Sensor Sender Sending Electric Gauge 0 150°c'

The switch was from 12Voltplanet and was

[P00747]      2     "ON/OFF/ON Toggle Switch - 25A@12V (1 Pole)" 
Price: £1.98
[P00749]      2     "Waterproof Cover For Toggle Switches" 
Price: £1.52

Similar to yours but with a metal toggle so a waterproof cover fits.

 

 

 

[Jonathan Kay]

"ON/OFF/ON Toggle Switch - 25A@12V (1 Pole)" 

Any particular reason for using that type rather than a two-position switch?

Thanks

Jonathan

PS:

Sorry about the images, they're the best I can do. 

They look OK to me... but you can put several in one post one after the other.

[SM25T]

All about a positive break between inputs, to avoid false indication through hysteresis in the gauge I recall. Also means you have a spare indicator switch readily to hand !

[tomwood]

Just to finish this off for the purposes of when it inevitably comes up in the archive when someone attempts to do this themselves.

I wired everything as described in my original post. It turned out I was wrong about the number of wires. On closer inspection I found that actually there is just a single green / blue wire feeding the left terminal on the original gauge. This is the existing temp sender wire responsible for giving the coolant temp to the gauge.

i did as suggested, prised this terminal out of the back of the plug and ran it to one side of the switch. Other side of the switch now has temp sender wire from sump tank attached to it. Middle terminal on switch has a newly made up wire that feeds into the connector (replaces terminal previously removed) and now feeds left terminal on gauge.

Fitting switch was simple, drill the dash in the right place and fit the switch.

i've got a diagram showing how this is all wired which I will upload later for future reference.

Tom

 

 

[tomwood]

Diagram as promised, hopefully its large enough to be readable, the club server seems to have resized it.

Few points about the diagram, The colours are purely indicative. In my case the original coolant temp sender wire was green & blue (purple wire on diagram). I have not had to run this wire myself from the temp sensor in the engine bay, this is already all wired in and I have simply re-used what was already feeding the existing coolant gauge.

The wire from the sump tank I did have to run myself (blue wire on diagram). This was the only wire that I had to pass through the rubber grommet ahead of where the gearstick is. You can of course use whatever colour of wire you want for this, likewise the new sender wire (orange on diagram) that will need to go from the central pole on the switch to the gauge.

Tom

[JonL]

Just resurrecting this thread as I am thinking of changing my oil pressure sender to mechanical, and making this mod to give me oil temperature also. 

Firstly thanks Tom for this info and diagram - very informative. I think I will do exactly as you have. 

My question is where on a 1.6 wet sump K series can I easily insert a temperature sender?

Jon

[Jonathan Kay]

Andrew Revill's advice, with photo.

Jonathan

[StevehS3]

If you have an Apollo tank there is a temperature sender fitted to the tank. The Apollo kit also had the toggle switch included, or at least mine did.

[JonL]

Thanks gents. I have an apollo tank so will have a look and see if there is a temp sender. I bought the car with the tank, so not got the toggle switch, but from the instructions above that doesn't look too challenging. 

 

[John Vine]

The Apollo temp sender is about half-way down (pic #4 here.)

JV

[Eckles]

Hi All, sorry to revive this old thread but could anybody help me with a bit of advice. I'm hoping to do this neat little mod so I can monitor oil temp on my 2.3 Duratec CSR. I've got the indicator toggle and the wires sorted but the question is where is best to insert the new water temp sender in order to get a reliable oil temp reading. The attached pictures are the bottom of the bell housing and there is already a temp sender there inserted into a sump plug which I presume is monitoring oil temp for the ecu but I'm not sure?? The other side of the bellhousing looks the same apart from the sump plug on the other side doesn't have a temp sender in it so am I best off removing that sump plug to tap a thread into it and insert the new temp sender there to monitor oil temp or does anybody know if there's a better place. There doesn't seem to be anywhere available to put the new temp sensor on the oil pump. The sump plug nut is approx 31.5mm and it's thread diameter is approx 27mm. Does anybody know the exact thread size of these plugs and where they are available from as caterham don't seem to have any. Thanks