Greeny72 0 Posted April 19, 2024 I’ve got a MK4 1979 cortina. I’ve just fitted a cluster with a rev counter from a MK3/4 but the temp gauge isn’t working. The temp gauge on my original cluster worked fine. If I short out the temp sender wire to earth the gauge works (sender unit is new). The sender unit is white in colour correct to the age of the car. I didn’t think that a different sender would totally stop the gauge working, just read incorrectly. would anyone know what colour to use? Quote Share this post Link to post Share on other sites
sheffieldcortinacentre 635 Posted April 19, 2024 Have you re wired the plugs as there in a different order between the different clusters. This will cause problems if not. There's a post on here somewhere about it. If not I should have some I can photo not show what order they go in. It's pretty simple job. Quote Share this post Link to post Share on other sites
Greeny72 0 Posted April 20, 2024 Yeah i found the post and wired as it says, even looking at Haynes manual wiring diagram. I short out the sender wire and the needle moves. Which points to a sender fault. But as the sender is brand new and worked fine with the original cluster. So thinking the sender is incorrect to the gauge. Is there a different colour sender for a MK3? The part number on the cluster is 74BB Quote Share this post Link to post Share on other sites
Greeny72 0 Posted April 20, 2024 Think it may possibly be a voltage regulator, not sure. The voltage at the sender (disonnected) is rolling/not stable. but if I short out the sender wire the gauge works. The resistance through the wire from gauge to sender is ok and not shorted. I’ve put a new sender on as well (they both read the same resistance) still nothing. Checked the voltage at the cluster using the cluster earth, is ok. Resistance through both gauges reads the same 12 ohms, and got good continuity thought the PCB at all points. The only thing is I’ve tried two voltage regulators, one from my original cluster which I know worked fine, and one from my the second hand one and both still not working (getting rolling voltage). Flashes from 11.9v to I can’t tell the lowest voltage as it’s so quick. Any advice would be appreciated. Quote Share this post Link to post Share on other sites
sheffieldcortinacentre 635 Posted April 20, 2024 No all use the same sender (white ring) & all gauges are same ( only needle colour & graphics changed). Hmm I'm not brilliant with this stuff, but it does all point towards sender problem. Let me have a think. Quote Share this post Link to post Share on other sites
