STE.W.

Hello,

A couple of months ago after seeking advice from you guys,I changed the ecu feed temp sensor for my cold start system.

Everything on that side is working fine

The problem I have now is ...

I was stuck in traffic in hot weather on Monday. I noticed the temps were climbing on the guage. Normaly at approx half way on the temp guage the fan would cut in. It is not doing this now

I have contacted my sub dealer and they have told me that the cold start ecu sensor is the same one that cuts the fan in and out?

Is this so??

If its not this ecu sensor I thought it was the one just between the alternator and the inlet pipes. Please can some one help.

They have advised that I should check to see if the fan itself isnt knacked.

Can someone advise the best way to check to see if I'm getting a supply to the fan or the wires etc.

I think the subaru guy is wrong with the switch location but hey who am I to know this sort of thing

Thanks in advance.

Ste.

STE.W.

Just had it confirmed that it doesnt have a seperate switch for the fan

This means either wiring fault, fuse or knacked fan motor.

Sorry to local dealer for doubting them

back to the drawing board tonight then.

Ste.

dnb

Get the car put on a select monitor when it's hot, and see if the ECU is doing what it should be... That will at least tell you if it is the ECU side or the fan side.

Do you know anyone you can borrow a fan from? They're only held in with 4 M6 bolts.

nom

I was just going to mention the fuse, but I see you've already thought of that one

STE.W.

thanks fellas.

Good idea bout borrowing a fan. I know someone who will help (Kurt R)

The select monitor will be one of my last resorts as the dealer is miles away and the costs will be high.

I'm gunna check the fuses again to make sure its not some voodoo fuse

Cheers
Ste.

STE.W.

Hello again.

I was hoping the fan would have been working by now but its not

The fan will work if take a live feed straight from the battery so its got to be a wiring/signal fault.

Will an auto electrician be able to find the fault and repair it or will I have to go to the dealer and put it on the select monitor??

As before the dealer option = a day off work, fuel and the cost of repair so I am trying to leave that til last.

Any one else with any suggestions?

Thanks

Ste

dnb

What year & model is the car?

I've got a wiring diagram for the pre97 Scoobs...

There's some relays that need to be checked as well on the left hand side of the engine bay. I assume you've looked at these.

STE.W.

dnb, My car is an my94 but its a Legacy Turbo

I've since spoken to the Service guy at my local dealer and he has advised that I should trace the wires back from the fan until I find the fault in the wiring.

He has been almost as helpful as you guys which is nice from a dealer. ( I wasnt expecting that level of help at all)

The wiring harnes runs along the bottom of the rad and then disappears into the engine bay. I am going to check the relays etc and cut open the loom and start tracing to find breaks or corrosion on dry joints etc.

Failing this I may have to fit some sort of after market thermo couple affair and take the control away from the loom . D Tweeks have a Pacet option or Revotec do an "in-line" tube with a temp controller kit built in which looks good.

I'm no auto electrician so please be gentle with me.

How do I check to see if the relays are working or not?

I changed the fuse to be sure it was ok and it hasnt made any difference.

I ran live to the fan and it kicked in. I could'nt get a live light on my circuit tester on any of the three wires that go to the fan connector plug.

The Subaru guy reckons no engine check lights should mean its not the ecu side it should just be basic wiring faults etc.

Sorry for the long reply but I thought the more info the better.

Hope you can keep feeding me with info.

Thanks for your help.
Ste.

dnb

It doesn't matter that it's a legacy turbo really. Car manufaturers love to reuse parts on different models - it's how they keep costs down... The wiring loom's probably just a couple of inches longer in some places!!

Relays are basically a little coil of wire (making an electromagnet) and a switch that is moved by the electromagnet, either to be open or closed.

They usualy have four terminals - 2 for the switch bit and 2 for the electromagnet bit.

You could do something similar to what you did for the fan motor to test them - connect a live and earth to the relevent coil connectors and see if it goes click! If you have a multimeter, you can connect it to the switch connectors and measure the resistance. If it goes to zero in one state and off the scale in the other then it's probably OK.

The other important thing to check is the earth connections on the car. They can get flaky on the older cars...

Hope this helps a bit - it's far easier to do (or show someone) than to write it down...

STE.W.

Thanks mate, I'll have a go over the weekend and let you know.

Have a gud un.

Ste.

Mark A

iTrader: (1)

What happens when you join the wires under dash to check for error codes and reset the ECU. On my impreza it pulses both the cooling fans. Don't know if this helps, might help you trace the fault while back tracking the live feed.
Can you check the live feed to the relay ?

What happens with the sensor when hot, ie is it warning the ECU its time for the fans to come on.
I would have thought that by bypassing the engine temp sensor with a bit of wire you should find out if the sensor is working.

I've got the manual for a legacy so could scan you pics of wiring diagram if needed.

Its mostly likely a very simple problem just difficult to locate.

Mark A

Turbo_Steve

My MY94 Legacy Turbo doesn't pulse, test or do anything when you connect the ECU wires together. The check engine light reads the error codes back, but the boost solenoid doesn't tick, the fans only spin for a few seconds and in fact everything stays much the same as normal. =shrug= that's assuming I have the right wires.


Apologies for hijacking, but wiring diagrams would be more than welcome, if anyone would mind e-mailing them to me!!!
I can't get enough info about legacies

Jolly Green Monster

iTrader: (4)

check there is enough water in the rad.. if it has been heating up it might have lost some.. no point aggrevating the problem.

Wire the fan to a switch so you can switch it on so as not to over heat until you have solved the problem.

The green plugs under the dash I believe do the test function which should spin the fan momentarily.. see it they spin.. you know it is the test one as all the relays click...

JGM

Turbo_Steve

See above: don't think Legacies behave that way on test.
Waiting to be corrected.

Jolly Green Monster

iTrader: (4)

so that will check his wiring which was the reason for connecting them to check the wiring?? dah!!

JGM

Turbo_Steve

D'OH!!!!!!!!!!!!!!!!!!

Remind me to pop to Halfords and pick up one of those Head/a$s extraction tools.

Apple

forgive me if I'm stating the obvious but does the temp sensor that's usually screwed into the rad somewhere actually work?

if it's not ecu side and the fans run by giving them a live feed then it looks like the water temp sensor might be ex / fuct etc. they aren't invincible...

with the engine cold / not running so you don't frazzle yourself or get caught in the belts etc , (assuming the wires are connected to the sensor with push fittings / plug with two wires in) have ignition on and short out the two connectors (on the loom side - not the temp sensor ) with a bit of wire - the fans should start indicating the temp sensor has had it... if not then it's not sensor unit and could be bad connections elsewhere

sensor units shouldn't be that expensive from motorist discount shops or even from dealer...

Apple

STE.W.

Morning chaps.

Thanks for all the replies over the weekend.

I've tried to trace the fault through the loom but have given up[img]images/smilies/mad.gif[/img].

I will connect the plugs together to see if it throws any error codes at me tonight. You never know.

As far as I know the sensor is the one that controls the cold start system as well as the fans but Ive only just changed that a month or so ago! Subaru have told me the rad doesnt have a sensor of its own - its all controled from the cold start one.

I'm well out of my depth with this now. I can do basic wiring but shorting out stuff and testing the wiring is beyond me.

If I cant sort it out tonight Im gunna buy one of those in line thermo couple things and by pas the ecu control. I can set the fan to come in between 70 and 120 deg C! Any one have an idea what temp the fan normaly kicks in on a Legacy T?? On my guage it would normaly be activated just about half way.

All your help is much appreciated guys

I THANK YOU.

Ste.

Oh on another point while I m here!!

Question: Does bubbling header tank water signify a blown head gasket? My mates Leg T was like a fish tank aerator system last night

Jolly Green Monster

iTrader: (4)

What Apple is saying makes sense.. I had discounted this as the Subaru dealer told you the other sensor.. but perhaps they are mistaken.. not near my car so cannot check if it has a sensor in the rad..

As to bubbling header tank on mates car, it could be a blown head gasket but more likely just an air lock in the water system releving itself.

Check for water in the oil (white cream on dipstick) and oil in the water.. keep a close eye for smoke from exhaust or water..
and if it doubt get a pressure test done on the heads. Check the heater works on hot as it might be that there is a leak somewhere and the water is slowly leaking and there is air in the system due to that. first place to no longer have water in is usually the highest point (the heater matrix) so no heating.. and obviously the coolant level.

JGM