Porsche Enthusiasts Club Forum

To quote myself from my fuel line thread I will carry on with the temp sender issue I had with my temperature gauge on this new thread.



The temp sender I found and mention above got lost in the post and after 2 months it took another month for them to send another out, I had ordered thinking this was coming from Portsmouth in the UK but once I had ordered I realised that it was coming on a slow boat from China, twice as it turned out!
As I say it got lost and they sent another one out.....3 months later, I had the sender at last but it didn't look the same as my original and even though they had quoted the part number 928.606.201.01 all the way through it was definitely different.
Has anyone else ever bought one of these and it has worked, I'm confused why they are quoting the correct part number if it doesn't work correctly or have I got a bad one?



I had to remove the inlet manifold to get at it, this was also because the wires had broken its connectors off the ends and I needed to get some crimpers in there to fix those.
Before I fitted the Chinese sender I tested it with the wires connected and ground to earth in various temperatures of hot water in various cups but it didn't register at all on the dash, I'm glad I didn't just fit it and expect it to work, I blamed it being a Chinese copy, I had wasted almost 4 months with this job.

So putting all that behind me I looked for the TD4 Freelander sender mentioned above but they looked totally different so I tried to order a genuine one again as I had no luck originally as nowhere had stock and OPC was saying no availability and they wouldn't know when one would be available until the end of August.
Luckily my OPC dug a little deeper and found one at the trade part of Reading HQ and managed to source that for me and I picked that up today and will be fitted that as soon as I've posted this up.

One reason for that is I'm asking a question regarding the wiring on the new genuine sender. My ends broke off the wires and the sender has two sizes for the end of the sender, does anyone know which colour wires goes to which connector, large or small to which?

I can have a look at mine for you tomorrow
And the TD4 sender is to replace the blue sensor at the front with the square connector
I have spoken to VDO about sourcing the gauge sender with the two spade terminals, they tell me it’s a dealer supplied part only

I just fitted the wires one way which didn't work so swapped them over and all is good now and I have a working gauge again. I did think the TD4 one did look like the ECU sender which is good to know if that ever fails.

I seem to have got the last temp sender in the UK, and everywhere else I looked showed on various websites but didn't actually have any stock.

I returning to the thread as I've gone back to having a non moving gauge again and I'm seeking a little more help.

I have been trying to figure this out for the last few months but have been stumped.

I checked continuity of the two wires from the sender to the dash plug, I found one that was fine but on rechecking I had continuity also on another wire at the plug end from the same wire, I can't find the wiring diagram for the dash on the 16v engine, I only have the Haynes manual to reference and that doesn't show it. I will come back to this later today when I re-test which wires I'm getting continuity to?



I have followed the Clark's guide and bought a potentiometer which did make the gauge move as I turned the dial so I am eliminating the gauge itself for the moment, it took a little guess work to set it up but was glad to see movement in the gauge.









I next tried to test the new sender with my meter and I'm getting nothing from that when testing ohms, I have tested one of the Chinese senders to compare and I do get an ohms reading so does that mean the new sender is faulty?



I have spoken the my OPC and he is finding out the warranty and exchange process but I am not sure why a new sender would be faulty? I have done zero miles since fitting it so I can't see it being the problem but if not what else could it be? I currently have it removed so it can be sent back if required, apparently they do have stock of these again so maybe next week I'll have a new one?

Does anyone have the wiring diagram handy, I just want to find out where the other cable goes that I have continuity with the sender wiring and hopefully it isn't shorted out?

All the 944 manuals and diagrams are on www.pdlibrary.co.uk

Thanks for the link Waylander, I spent an hour or two last night frying my brain trying to match up the various wiring diagrams, I took some screenshots but wasn't really sure what I had was correct?

I went to compare what I had today and the wiring colours don't really match what I have on my sender, both of the wires look blue/green, it's hard to make them out fully being under the inlet manifold, so I just went back to testing.

I made sure I had continuity to the dash circuit board, not just the plug this time which was fine, pin 13 on the plug went to the two Green circles and pin 12 is the Red circle.



I also wanted to work out which wire connected to the warning light on the temp gauge as I hadn't worked that out yet, I would also like to work out which pin on the sender is which as this would save some time messing, I just put a small battery on the cable to illuminate the warning light on the dash to work that one out.



Does anyone know off hand if the large or small pin on the temp sender is the warning light?

you need to match your car to the year and area for the absolute correct diagram, but they are all the same in connection, so you dont need to worry about colour, just point to point, so if pin 12 is sky/blue/pink in your car and blue on the diagram, as long as they connect to the correct pins its fine

the two black lumps commonly refered to as rugby balls, with the 8mm nut in the middle, have you taken those off and given the pins and the brass bits a good clean with some wire wool, that is a very common issue for duff readings, and whats with the red connectors going to the buld holder, is that because the track and plastic is fried, too big wattage bulbs,
I would also give the edge connectors a little wire wool action very gently, and if you break one of the arms off the plugs you can still buy them, the side unclips and you can swap the plug, take a photo first,

you can put some electrolitic grease on the connectors, save them corroding again

I did yes, I have cleaned them up in the past and although they looked mint I gave them another clean up with a little emery and IPA.

OPC are ordering me a new sender today so I guess I'll find out if it is that or not in the next few days?

looking at the image of you with the meter in the sensor, i doubt very much its between the pins, it will be the resistance between each pin and ground, the sender should have the VDO number on it see if you can find a tech sheet for it, if not email the tech dept at VDOshop, they are very helpful, they should be able to tell you which is the light switch and the guage

when it comes to diagrams, try this

Sorry Waylander, the image was probably misleading and as you say should go from the post to the sender body, the picture is of the fake sender and the surprising thing is there is continuity between the posts when there shouldn't be. The genuine sender had continuity between the body and only one post, the other had nothing.

And after months of messing with this I have a resolution to the issue, I collected the new sender from OPC yesterday, they gave it me in the hope I return the faulty one when I'm ready, if indeed is was faulty, and I tested it in a cup of boiling water and immediately got a reading on the gauge, I've now fitted it and filled it back up with coolant, ran it up to temp and the gauge works again. I discounted the previous new sender because it was new and why I tested everything else what seemed endlessly before pointing the finger at the sender again.

For future reference I also worked out that the larger post on the sender is for the gauge and the smaller one is for the red overheating light.