heat light on dash coming on..

[insanesam]

hey,

have had a look through the forums and the net but can't seem to find someone with the same issue...
have just bought an mx5 and notice that after driving for 5-10mins, the heat light on the dash starts to glow dimly then ends up coming fully on. once on, it will remain on for the remainder of the drive but then as soon as the car is turned off (and then back on) it has gone off. these lights generally point to the cat overheating however i was of the impression that they are a "fuse" type sensor that once it overheats, melts causing it to ground and light comes on. i dont understand how it is coming on slowly after some time and then deciding it is fine again!??! car seems to run fine, and did not notice it until we took her out and floored it partner reckons i should just have the cat cut out and replaced with an empty section which seems to be a common way to go? what could be causing such an issue?

cheers

[mazline]

what is your car ?,Damn hard to comment when you have have no idea what model you have.
profile details do help

[insanesam]

hey,

sorry... literally just joined up to the forums and havn't had a chance to figure out how it all works yet. it is an NA (1992) 1.6l smurf blue one

cheers

[Mikkels]

Hi I had that problem and it turned out to be the alternator not charging properly. You can check if your alternator is working by checking the voltage at the battery with the engine running. The manual wil tel you the voltage you should see which is from memory above 13 volts.

I had a couple of lights coming on on the dash often lit weakly. That went on intermittently for about a year then they came on more solidly one rainy morning. Then the wipers quit but luckily the engine kept going to get me to work. I had a spare alternator hanging around. Fitted that and all cured. You may want to check your belt tension first as that will also do it.

Welcome to the forum and have fun with your new purchase.

Don

[insanesam]

had the trans serviced and have been told its in brilliant condish (virtually nothing in the pan - oil a bit dirty but not bad) and that they are just generally quite lurchy due to being so light and RWD. expensive way to be told that i am just paranoid! although nice to have it done and know all is fine. heat light is still coming up however i can definitely hear a belt slipping on occasion. dad had a look while i had it running and reckoned it was the power steering belt and not the alternator belt... could this be causing the heat light to come on?? the battery/charge light does not light up (except for check when ignition is turned on - ie bulb works) which it seems like it does for those experiencing this issue due to the alt belt slipping... cheers