Heater staying on

Mk1 gt tubby

Fresh Recruit
Hi All,

Just started experiencing problems with my heater. It's a mk1 GT. The heater will switch on and off on its own and there is a burning smell??? I think it could be a resistor but I don't know if it's changeable or where it's located. The blower still blows hot air so I don't think it's the blower motor.

Thanks in advance
 

Jay

Admin
The burning smell would worry me.

If you take the glovebox out it should reveal the heater boxes and the resistor. Pretty sure it's a bolt in/bolt out component. Other thing you could do is drop the blower motor out (three bolts on the underside of the system). Wouldn't be hard for debris to jam it and make it burn out.

Keep us posted on what you find please.

Jay
 

Mk1 gt tubby

Fresh Recruit
The blower still works fine it's just powering up on its own. If I pull up with the heater on and switch the ignition off it goes off as it should. After 30 seconds(approx) something clicks like a relay and the heater turns on even though the ignition and the heater switch are off.
 

Jay

Admin
Strange one.

Also worth taking the control panel out and checking the wiring there incase something it shorting out.

Does the radio start up too? Only asking in case it's the ignition switch that's sticking.
 

SKINY

Lifer
Yea the resistor is literally right in front off you when you take the glove box out, either 2 screws or 2 bolts and 1 plug.
Where is the smell coming from ? I've sold a good few Toyota ignition barrel connectors over the years so they do fail
 

Mk1 gt tubby

Fresh Recruit
I thought that myself about the ignition switch but because the heater still powers up whilst switched off at the heater switch I kinda ruled it out. There is a clicking from the glove box area when it powers on so I will check 2moz.
 

Mk1 gt tubby

Fresh Recruit
quick update.

First of all I checked the actual switch on the centre console that controls the heater blower and blower speed. I disconnected the wiring plug off the back of the switch and turned the ignition on and the heater blower powered on. I then disconnected the wiring plug from the blower and it was showing 12v as soon as the ignition was switched on??? I have put my own switch in that wire so I can turn it on and off until I find the cure. Pointing towards the ignition at this stage as Jay and Skiny have mentioned. What connectors do I need for the ignition?

Also noticed that my clock on the dash flickers light to dim sometimes as if your turning the head lights on?

Also oil pressure/oil temp gauges needles bounce rapidly sometimes. If i use power windows or any other electrical component they stop bouncing instantly. These are mounted in the centre console so will have to check all wiring and earths also.

Thanks for all the info
 

Jay

Admin
Strange.

I'd recommend going through the earth points in the dashboard loom. There's one at each A pillar, one at the dash clocks and another in the centre (something tells me it's up at the dash clock but I could be wrong).

There's four you can check in the engine bay. DS engine mount to chassis, top of gearbox to passenger side chassis rail, injector wiring to intake manifold and the main one, battery earth strap to PS gearbox mount.

Also check your thermostat housing sensors are all connected properly as they can cause the temp gauge to mess about.
 

SKINY

Lifer
Yea check and clean the earths if they need cleaning bud
The dash clock dims when you put the lights on so that's at least normal behaviour :)
The ignition switch is attached to the end of the barrel, from memory there are a few small starheads hold it in place then it pops off on a short loom to the connector, I've seen loads off these fail with age
 

dark_knight

Member +
quick update.

First of all I checked the actual switch on the centre console that controls the heater blower and blower speed. I disconnected the wiring plug off the back of the switch and turned the ignition on and the heater blower powered on. I then disconnected the wiring plug from the blower and it was showing 12v as soon as the ignition was switched on??? I have put my own switch in that wire so I can turn it on and off until I find the cure. Pointing towards the ignition at this stage as Jay and Skiny have mentioned. What connectors do I need for the ignition?

Also noticed that my clock on the dash flickers light to dim sometimes as if your turning the head lights on?

Also oil pressure/oil temp gauges needles bounce rapidly sometimes. If i use power windows or any other electrical component they stop bouncing instantly. These are mounted in the centre console so will have to check all wiring and earths also.

Thanks for all the info
Besides the gauges you mention, are there any other after-market electrics / electronics installed..?
 
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