HELP!!! Intercooler fan light on and intercooler fan not cutting in

[GT-Thunder]

Hi All,

Right need some help fellow MR2 Guru's. Myself and a couple of friends have been trying to diagnose the problem and conducted the below with the limited time we have had.

I have a issue with the intercooler fan. My MR2 was stored over winter as a bit of garage queen. I broke her out for a run to a exhaust specialist a few weeks ago. On the way the engine fan light on the dash came on. It went off once and the fan came on but then stopped with the dash light on. I have done a lot of tests as followed

1. Disconnect temp sensor on engine lid - engine was at cold start up and engine bay intercooler fan comes on.
2. Plugged temp sensor on engine lid back on, the fan stop, allowed car to warm up and when hot dash warning light comes on and the intercooler fan is not coming on.
3. Discon the temp sensor and the intercooler fan wont come on engine hot.
4. Tried a different relay in engine compartment for the vent relay and also cooling fan control module next to the ECU in the boot but the only one I had to hand was from a NA and different part number. Still no luck

Let the car cool down to cold and did no. 1 & 2 again and the same result. It seems the warning light comes on and the fan will not kick in when the engine is hot but when cold or allowed to cool down it will kick back in with the temp sensor disconnected [point 3]

Any one had this issue? The fan is aftermarket but wired into the normal loom via the plug on an aftermarket intercooler which was on the car when I bought it [not old kit] - car run fine to JAE last year and back with no issues etc...

Before trying to swap a fan out is their anything else to check - random relays, fuses etc...

[Draven]

Altimeter on the cable going to the fan

[/list]

[Peter Gidden]

Altimeter on the cable going to the fan

Ah. Yes, The old "only works up a mountain" problem.

[Draven]

Altimeter on the cable going to the fan

Ah. Yes, The old "only works up a mountain" problem.

Thats the one..


Then if that doesn't work you can use a voltimeter..

[shinny]

The fan is aftermarket but wired into the normal loom

That could easily be the issue. The fan control box measures the current running through the fan. It's expecting to see the standard fan but it will have a tolerance level that will accept other fans (in fact, I have exactly the same setup with the fan relocated to the engine lid). But, if the current is too low or too high then the fan gets switched off and the warning light comes on. So, I would hypothesise that when the fan is cold it draws less current that when it is warm (resistances generally reduce when warm, hence more current / power draw). I could raise another hypothesis regarding voltages and revs; the alternator doesn't produce full voltage at idle and more voltage means more current. Therefore the fan may be out of tolerance above, say, 2000rpm meaning it faults while driving while being fine with the engine off.

Bear in mind that once the red fan light is on, the fan will not even be tried again until the ignition has been turned off and on again.

[GT-Thunder]

Thanks for quick reply guys

I am not electrical at all so what would I be looking for here? and if it is not showing any power to it when hot what would this mean?

I don't have Voltmeter or a Altimeter but look to get one.

Appreciate all advice

[GT-Thunder]

The fan is aftermarket but wired into the normal loom

That could easily be the issue. The fan control box measures the current running through the fan. It's expecting to see the standard fan but it will have a tolerance level that will accept other fans (in fact, I have exactly the same setup with the fan relocated to the engine lid). But, if the current is too low or too high then the fan gets switched off and the warning light comes on. So, I would hypothesise that when the fan is cold it draws less current that when it is warm (resistances generally reduce when warm, hence more current / power draw). I could raise another hypothesis regarding voltages and revs; the alternator doesn't produce full voltage at idle and more voltage means more current. Therefore the fan may be out of tolerance above, say, 2000rpm meaning it faults while driving while being fine with the engine off.

Bear in mind that once the red fan light is on, the fan will not even be tried again until the ignition has been turned off and on again.

Thanks Shinny, it is really odd as the car ran fine before winter on a number of short and long runs and never had a issue. The previous owner did the set-up and we were catching up and he never had the issue with the light and fan not coming on.

Car electrics are a bit of mystery to me and keen to nail this one quickly

[GT-Thunder]

Right problem identified.

The little wiring section/loom the intercooler fan plugs into in the engine bay has a fault in it, guess a minor break in one of the wires and during my investigations today identified this was causing the fan not to work.

Anyone know if you can buy this section/loom wiring section from MR T and a part no?

If not will look to source a used on or get it repaired by auto electrician at my local garage.

[Draven]

Thanks for quick reply guys

I am not electrical at all so what would I be looking for here? and if it is not showing any power to it when hot what would this mean?

I don't have Voltmeter or a Altimeter but look to get one.

Appreciate all advice

Don't ask for an altimeter.. that is for measuring how high you are up a mountain

Voltmeter is what you want..