temperature gauge/ heater lukewarm

Usually with this it's the thermostat, but also check the viscous fan which can seize with great regularity and cause severe damage if not checked. The fan is not designed to spin at the same speed as the engine and if it's seized will keep the temperature of the engine down making the heating system ineffective - it will also use more petrol as the engine never gets to working temp.

To check, start your engine and leave it running for ten minutes. With the bonnet up, switch off the engine and watch the radiator fan. If if stops dead when the engine stops, then it's seized or partially siezed and on it's way out. If it keeps on spinning and slows down gradually, then it's fine.

A seized fan can break it's blades which, flying off at 2500RPM can caused a lot of damage...replacement viscous units can be bought from various sources and their fitting is easy.

This should be part of your regular and routine checks but never seems to get done

Cheers

Martin

Firstly I must say that I'm not a Jag expert, but I have worked on all sorts of cars for a living for over thirty years now. My philosophy is to try the simple, quick and inexpensive things first. You may have done this already, but did you check the dashboard illumination dimmer switch - sometimes it's turned down to the 'low' position by accident.

The lack of reverse lights may be simply both bulbs blown. Reverse light switches have a habit of failing. I don't know if your car is manual or auto, but on manual boxes the switch is usually mounted on the box casing. Autos may be the same, or they could be part of the start inhibit switch (which stops you starting the car unless it's in 'park' or 'neutral'). Try removing the connector and, if there are only two wires at the switch, bridge the two contacts (with ignition 'on', of course) to see if the lights illuminate.

For your fog lights, try bulbs again. Failing that, the relay which operates them is a good place to check (I'm sorry, I dont know where it is, but I do know there are some lighting relays under the bonnet). Fuses are definitely worth looking at also.

Good luck!

thanks jaybee,,had an idea it may be faulty or even missing, have ordered new part..thanks for your response..now any good on the electics..hahaha,, got a few issues with ;
reversing lights not working
front fogs
dash lights
door mirrors and most frustrating,,speedo needle stops at about 20mph
using sat nav to give speed indication at the moment.
will be making further checks on fuses etc when the weather improves but so far not found any that have blown..over to you friend,,any ideas,,thanks again.john..

Sympoms are classic faulty thermostat (stuck open allowing too much cooling), or possibly missing thermosat (removed).

have an 89 3.6..purchased is sept, heater was ok but now the weathers so bad / cold (the blower and controls etc, all seem to be working fine ) the airflow output is barely lukewarm no matter how i try to adjust the controls, the engine temperature gauge reads barely above " C "..any ideas how to rectify..i would say im quite competent mechanically and with auto electrics so nothing involving cars fazes me,,except stipping things down to get to the faulty bits..why are they always situated in the most awkward of places..?