CASwede Posted March 19, 2014 Share Posted March 19, 2014 I've been dealing with a temperature gauge that consistently reads cold. I don't believe the engine is actually running cold, and need a part number for the lower coolant temperature sender on a ZX3 Zetec. I believe the issue is only affecting my viewing of the temperature gauge. I believe the Pectel T2 is getting the correct temperature from the upper sender. I've found plenty of lower gauge senders on the internet, but they are all two blade (not confusing the two pin top sensor for the bottom sensor). The wire from my gauge is only a single blade female connector to a single blade sender. I did see a comment in a post that mentioned the lower sender was replaced in production with a two blade model, the latter of which I can find many examples for sale on the internet. I can't find a single blade model, although I can't discount the potential that one is in front of my nose. Link to comment Share on other sites More sharing options...
pi7ot Posted March 19, 2014 Share Posted March 19, 2014 I believe that your sensor is not grounded. Try a short piece of wire with a male spade connector on one end and a loop on the other. use an existing bolt/stud to hook the loop end to a metallic area of the head. then using a small hose clamp, clamp the spade terminal, to the metal body of the sensor after sanding the body for good conductivity. m Link to comment Share on other sites More sharing options...
coffee break Posted March 19, 2014 Share Posted March 19, 2014 There does appear to be enough corrosion to cause grounding issues. The sensor could be removed and cleaned with a wire brush by hand and re-installed. Link to comment Share on other sites More sharing options...
CASwede Posted March 20, 2014 Author Share Posted March 20, 2014 I'll clean it up, and will run a ground to it. Could that be throwing off the resistance reading to the gauge? Link to comment Share on other sites More sharing options...
CASwede Posted March 20, 2014 Author Share Posted March 20, 2014 The gauge did not enjoy the ground. It just pegged the gauge to max as soon as the car started. The gauge is consistent, just off. Since I can't find a similar part, my guess is that it was replaced with something not calibrated to the Caterham gauge in order to accommodate the connector that came with the loom. I can probably live with it. I'll just turn my head to the left a little when I look at it. Link to comment Share on other sites More sharing options...
xcarguy Posted March 20, 2014 Share Posted March 20, 2014 The gauge did not enjoy the ground. It just pegged the gauge to max as soon as the car started. The gauge is consistent, just off. Since I can't find a similar part, my guess is that it was replaced with something not calibrated to the Caterham gauge in order to accommodate the connector that came with the loom. I can probably live with it. I'll just turn my head to the left a little when I look at it. CASwede, If you don't mind spending the money, purchase a 'relatively' cheap temp gauge (mechanical) from O'Reilly, Auto Zone, etc. It will come with a sending unit; hook up the gauge (outside of the car) and see what it reads. Alleviate the possibility of the problem being something other than the sending unit . . . . . just a thought. :smash: Link to comment Share on other sites More sharing options...
CASwede Posted March 21, 2014 Author Share Posted March 21, 2014 (edited) That's a good thought. If I can find a mechanical that will fit in a Caterham dash, I might just discard the original. What's got me so puzzled is how the connector on the loom doesn't match any sender that I can find for the engine, other than the one that is currently installed. I've compared two 80 degree thermostats, and the gauge is consistent between them. Fans cycle in and out normally after the thermostat opens. I'd check what the Pectel ECU thinks the temperature is, but no software/no connector. Edited March 21, 2014 by CASwede Link to comment Share on other sites More sharing options...
breezy7 Posted March 21, 2014 Share Posted March 21, 2014 (edited) My Caterham had a plug above the closeout panels near the driver's left knee. It is a standard OBDII connector for reading fault codes and will give the temp the ECU is seeing. I don't know what years Caterham USA included it in their wiring harness though. The sending unit in your picture is what I remember on my car but it did have a ground wire attached to the unit. I thought this issue had been addressed before on the forum but a quick search didn't show any results. Edited March 21, 2014 by breezy7 Link to comment Share on other sites More sharing options...
xcarguy Posted March 21, 2014 Share Posted March 21, 2014 That's a good thought. If I can find a mechanical that will fit in a Caterham dash, I might just discard the original. What's got me so puzzled is how the connector on the loom doesn't match any sender that I can find for the engine, other than the one that is currently installed. I've compared two 80 degree thermostats, and the gauge is consistent between them. Fans cycle in and out normally after the thermostat opens. I'd check what the Pectel ECU thinks the temperature is, but no software/no connector. CASwede, If you do decide to replace the gauge, I might consider another electric unit; easy, clean install. I was suggesting the mechanical for testing because I think it may be cheaper than an electric gauge. Again, just a thought. Link to comment Share on other sites More sharing options...
CASwede Posted March 21, 2014 Author Share Posted March 21, 2014 I'd like to keep the sender electric, and just plug it into the loom I have. Problem is finding an electric sender with the right terminal for the connector on my loom. I don't think I can re-wire the connector for a two blade...hmm, or can I? Link to comment Share on other sites More sharing options...
xcarguy Posted March 21, 2014 Share Posted March 21, 2014 I'd like to keep the sender electric, and just plug it into the loom I have. Problem is finding an electric sender with the right terminal for the connector on my loom. I don't think I can re-wire the connector for a two blade...hmm, or can I? Might give this a shot: http://www.ebay.co.uk/itm/Smiths-Water-Temp-Sender-Telemetrix-International-Gauge-/360843413031 Link to comment Share on other sites More sharing options...
CASwede Posted March 21, 2014 Author Share Posted March 21, 2014 That looks good! I'll see if I can track down the resistance ranges to see if will will come in close. Thank you. Link to comment Share on other sites More sharing options...
Klasik-69 Posted March 31, 2014 Share Posted March 31, 2014 I think that Caterham changes the sender in their engines to accomodate their gauges. The stock Ford Focus 2.0L DOHC engines of 2003-04 uses a sender that has a different plug connection than the single spade like yours of mine, and I think the second terminal in that is the service ground that the Caterham unit fails to provide, hence the need to make your own ground. You can test your sender by reading the resistance to ground (the body of the sender) cold then compare it after immersing it in boiling water. If the resistance is the same, you have a dead sender. If your sender is good in this test, better check your connections. If the gauge pegs when you ground your unit, the gauge may be the culprit. If its of any benefit, mine takes a while to warm up to the 80 degrees centigrade, then it stays steady on or off the track, in summer or winter. Rock steady. Link to comment Share on other sites More sharing options...
BruceBe Posted April 6, 2014 Share Posted April 6, 2014 I believe that your sensor is not grounded. Try a short piece of wire with a male spade connector on one end and a loop on the other. use an existing bolt/stud to hook the loop end to a metallic area of the head. then using a small hose clamp, clamp the spade terminal, to the metal body of the sensor after sanding the body for good conductivity. m This is the correct advice. It sounds like the main terminal to the sensor was grounded, not the body. Create a wire with a small ring terminal, and a large ring terminal. The large ring terminal would be installed under the sensor, while the smaller ring terminal would be installed under the head of a bolt that secures the Thermostat housing to the head. See the black wire in the attached photo -Bruce Link to comment Share on other sites More sharing options...
CASwede Posted April 7, 2014 Author Share Posted April 7, 2014 Interestingly, when I tried that grounding method it simply stuck my temperature gauge needle to the max upon receiving electricity from the car. My current sender does appear to be working, just in the wrong range for the gauge. I found a couple of sources for generic blade terminal senders in various resistance ranges. About a week before that I found the technical specs on the resistance range of stock two pin Ford senders for Zetec engines. Once I re-marry the two sources of info together, I'll spend the $15 to see if it's a fix. But work and little league are conspiring to keep me away from the 7 for another week or two. Link to comment Share on other sites More sharing options...
CASwede Posted April 7, 2014 Author Share Posted April 7, 2014 If the gauge pegs when you ground your unit, the gauge may be the culprit. And then if my $15 test doesn't pan out, a new gauge is probably in order. I'll simply have to decide if I want it to say Caterham in little letters on the face. Link to comment Share on other sites More sharing options...
xcarguy Posted April 7, 2014 Share Posted April 7, 2014 Okay, taking another stab; is the engine block grounded to the frame with a a ground strap . . . such as this (braided ground strap)? http://www471.pair.com/stalkerv/gallery2/main.php?g2_itemId=23639 :rofl: Link to comment Share on other sites More sharing options...
CASwede Posted October 27, 2014 Author Share Posted October 27, 2014 My other car projects delayed the final answer on this one, and I wouldn't bring it up other than it drives me crazy to read threads that don't come to a conclusion. The sender was simply not the correct sender. The original sender was properly grounded to the block with a wire attached to the sender threads that I had not been able to see until I took apart the housing. There was proper grounding from battery to block to frame. The measured resistance was different between the old sender and the new sender. I stripped the sender wires, and crimped new fittings that would attach to the new sender. The new sender sends a consistent 80C/180F temperature to both the old Caterham gauge and the new AutoMeter gauge, so I'll keep the Caterham gauge in the car. Link to comment Share on other sites More sharing options...
xcarguy Posted October 27, 2014 Share Posted October 27, 2014 It's about time!!!!! Link to comment Share on other sites More sharing options...
James A Posted October 29, 2014 Share Posted October 29, 2014 I've just been through this, here is the correct sender: http://www.ebay.com/itm/VDO-323-057-300-deg-F-Temperature-Sender-/311043168321?pt=Motors_Car_Truck_Parts_Accessories&hash=item486b9e1841&vxp=mtr Make sure the body has the ground lug attached when you reinstall it, the old spade lug fits right on the new style top, you just push it on with the split side down. Jim Link to comment Share on other sites More sharing options...
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