BLACKJACKS Posted February 6, 2010 Share Posted February 6, 2010 HELLO all i need your help n reg 300 tdi auto diesel right i have a problem with my temp gauge not reading now if i stick the wire on the block gauge reads hot then stick it on the sender unit reads nothing . so in goes new sender unit and no joy still reading nothing so i have a earth problem. has any one had the same problem and any ideas on how to fix it ... all is working got loads of heat and its just the gauge that isnt working ...... paul Quote Link to comment Share on other sites More sharing options...
jakebullet Posted February 6, 2010 Share Posted February 6, 2010 hi there, when you say a new sender are we talking a new genuine sender, or pattern? the reason i ask is there are several type of 'universal' ones. some of which dont send the correct type of signal. jake Quote Link to comment Share on other sites More sharing options...
gripper Posted February 6, 2010 Share Posted February 6, 2010 i would agree there, it it works when earthed on the block then the sender is definately the problem, it is possible for a new one to be faulty. have you checked to make sure there is not an air lock as the sender wouldn't work unless it is immersed in water. Quote Link to comment Share on other sites More sharing options...
BLACKJACKS Posted February 6, 2010 Author Share Posted February 6, 2010 sorry yes it was a genunie got from hunters main dealer this morning . well ive chased the wiring loom down and nothing .would it be the housing it screws in to for some reason im toal lost on this . paul Quote Link to comment Share on other sites More sharing options...
cipx2 Posted February 7, 2010 Share Posted February 7, 2010 1. Check the temp sensor. Disconnect the temp sensor and measure it with an ohmmeter. When the engine is hot, it should have about 35-30 ohms (the higher the temp -> the lower the resistance) 2. Check the gauge. Disconnect the temp sensor and replace it with a 100 ohm potentiometer to simulate the sensor. Preferably use a linear taper pot (i.e. not logarithmic taper pot). On the dial gauge there are 4 indications (lines): #1 - the bottom one, #2 and #3 - the two midle ones connected with an arch and #4 - the red top one. Set the pot at ~50 ohms -> the needle goes to #2 Set the pot at ~30 ohms -> the needle goes horizontal, aprox midpoint between #2 and #3 Set the pot at ~20 ohms -> the needle goes to #3 Values are from memory but they are within 10%. If you don't have/find a pot, you can use five 100 ohm resistors: - 2 res in parallel= 50 ohms - 3 res in parallel= 33 ohms - 5 res in parallel = 20 ohm Or use only 3 res and do only 2 tests. Quote Link to comment Share on other sites More sharing options...
p76rangie Posted February 7, 2010 Share Posted February 7, 2010 You might want to check whether it is earthing out properly by using a multimeter on the base of the sender and to a different earth while the sender is mounted. Quote Link to comment Share on other sites More sharing options...
errol209 Posted February 7, 2010 Share Posted February 7, 2010 You might want to check whether it is earthing out properly by using a multimeter on the base of the sender and to a different earth while the sender is mounted. Did you use PTFE tape to fit the new one? Quote Link to comment Share on other sites More sharing options...
BLACKJACKS Posted February 7, 2010 Author Share Posted February 7, 2010 does that help ill try that but if the sender unit is earthing out on the casing wouldnt the gauge be on hot all the time . but i went out to day and the gauge well the niddle comes off the c and sits on the white bar and stays there total got me . i know that i keep getting green ended sender units would the black one work .but going to try the PTFE tape . Quote Link to comment Share on other sites More sharing options...
gripper Posted February 7, 2010 Share Posted February 7, 2010 don't use ptfe tape that would just create an insulated bit so it couldn't earth properly, as stated fit it without any tape and try a continuity test from the body of the sender to another earth point, it should be good continuity with virtually no resistance, if there is then you may need to fit a new earth strap to the engine across to the battery earth. you could try some jump jeads from engine to battery neg to try if that sorts it then new earth strap it is. Quote Link to comment Share on other sites More sharing options...
BLACKJACKS Posted February 9, 2010 Author Share Posted February 9, 2010 well ive tryed all the earths and cleaned them up and replaced the ones that broken off in my hands . ive even tryed the earth lead to the battery then to engine and still no joy got loads of heat now and still no temp gauge . oh i did change the temp sender on top off head /rocker cover but no joy . any more things to check this is baffleing me .ive taken the dash out of my other disco and still no joy mmmmm going bold with all the head scratching lol Quote Link to comment Share on other sites More sharing options...
BLACKJACKS Posted February 13, 2010 Author Share Posted February 13, 2010 This all working and fixed and god i have to say the heater is so hot if i have it on feet it burns . i couldnt work it out so i took it to andy at.. www.challengemotorsport.com i would say top workmanship and very help full .if any work needs doing give him a ring ...big thumbs up from me Quote Link to comment Share on other sites More sharing options...
shauniedawn Posted February 13, 2010 Share Posted February 13, 2010 So what was the problem? Shaun Quote Link to comment Share on other sites More sharing options...
BLACKJACKS Posted February 14, 2010 Author Share Posted February 14, 2010 well he took off the thermostat houseing cleaned . new gasket /new thermostst/new sender and bleed system let it run .was told to run it with bonnet down as it warms up faster and with heater off to start .and yes the gauge moved .when neddle in middle of guage heater on loads of heat .so all it needed was a dam good clean up and bleed system up .well happy now on to the next job now lol .. Quote Link to comment Share on other sites More sharing options...
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