Intercooler fan on constantly - Help with wiring, pic included

[Mr2Owner]

Does the fact I've got 12V at the fuse, but only the 1.56V back at the Fan Ecu on Pin2 indicate the problem is in the wiring between the Fuse and the Ecu?

Is there any point checking the dash bulb at this stage?

[Mr2Owner]

@mr2magic - I should get some more time to go at this again tomorrow. Do you think I should still dismantle the cluster and check for 12v at the dash bulb, or have we identified the problem to be in the wiring from the fuse back to the fan Ecu pin2 and so should I concentrate on tracing that wire for a fault?

Cheers

[mr2magic]

I don't know if the misding voltage at pin 2 can cause this condition! What i do know is that the bgb says you should have 12v and you don't. I also know that if there is a problem in the fan circuit the buld will light....something yours isn't doing. Based on this i qould solve the problem i know of before trying to find the next one

[Mr2Owner]

I don't know if the misding voltage at pin 2 can cause this condition! What i do know is that the bgb says you should have 12v and you don't. I also know that if there is a problem in the fan circuit the buld will light....something yours isn't doing. Based on this i qould solve the problem i know of before trying to find the next one

Sound, that makes sense all right, Ill try to solve the bulb not lighting issue first. I've removed the dash cluster today, do you happen to know which bulb is the fan bulb from the pic attached?

[mr2magic]

Of course... I know my car like the back of my hand. If it's the same us usdm then its the bottom left bulb in your pic.

[Mr2Owner]

The one under the blue connector thing, cool , i'll check that bulb to see if its blown tomorrow evening.

[mr2magic]

You could also just hold the cluster against the light and check whether the symbol is an engine with a massive fan in front

[Mr2Owner]

You could also just hold the cluster against the light and check whether the symbol is an engine with a massive fan in front

Howdy, I checked the bulb there tonight. It looked ok as in the wire inside wasn't broken but it failed the continuity beep test.

I pulled out the oil can bulb to see if it would pass the continuity beep test and it did, so it seems the Fan bulb is dead. When I hold the cluster against the light as you suggested, I can't actually make out the fan symbol at all, but I can make out the oil can, seatbelt, door open and engine management, maybe this suggests the fan bulb has been blown a long time and the symbol has faded due to never been lighted up in a long time. I think theres 6 bulbs in that area, but I can only make out 4 symbols.

Anyway, I suppose the next thing to do is fit a new bulb, and connect everything back together and see if the dash fan bulb is lit up then?

[mr2magic]

Ok...just checked a spare jdm cluster i have here.....it's different to the usdm! The bulb your looking for is still left hand side but the top row middle

[Mr2Owner]

Ok...just checked a spare jdm cluster i have here.....it's different to the usdm! The bulb your looking for is still left hand side but the top row middle

Cheers, I can see the fan symbol faded in the light now. I tested this bulb and it looks ok and passed the continuity beep test whilst in the bulb holder. I'll fit a new bulb to be sure.

If the bulb is ok, whats the next step, start looking for the missing voltage from the fuse to the Ecu? Can't see that being too easy or much fun.


Edit: Had another look at the car now.
The bulb works as the symbol is on the dash when ignition is turned on just before starting. The symbol goes out when I start the car. Also, when I unplug the fan Ecu with the car started the dash symbol still remains off. Should the dash symbol light up with the fan ecu unplugged?

Could a dodgey fan relay be the problem? Maybe I should replace the relays next? Or should I splice the pin2 wire into the pin3 wire to force it to have 12v and see if that makes the fan stop spinning? Sorry for all the questions, haha but i'm a bit stuck now.

[pbmr2]

test the relay, the bgb has the info.

[Mr2Owner]

test the relay, the bgb has the info.

Hiya, I have some of the BGB downloaded but can't find the page "CO-23" which describes testing the cooling fan main relay. Feel free to post a link or a pic if you have it.

Am i correct in saying the 3 fan relays in the front bonnet are for the radiator fans and the fan relay in the rear engine compartment is for the intercooler fan?

[mr2magic]

according to the bgb, the wire that should have 12v but doesn't isn't switched over the relay but over the ignition switch. You may have a problem with the relay but as i advised - solve the problem you know about before solving anything else.

And yes...you should now start tracing the 12v back towards the 7,5A fuse and beyond.

[2mad]

This was just to much of a headache , fitted a manual switch and relay .. job done

[Mr2Owner]

according to the bgb, the wire that should have 12v but doesn't isn't switched over the relay but over the ignition switch. You may have a problem with the relay but as i advised - solve the problem you know about before solving anything else.

And yes...you should now start tracing the 12v back towards the 7,5A fuse and beyond.

Thanks for the info on the pin2 wire not being switched by the fan relay. Perhaps there's an ignition switch relay that could be at fault?

When you say fix the problem we know about first, do you mean the problem being the dash bulb not lighting to indicate a fault in the fan circuit?

Would connecting in a 12v feed from pin3 to the pin2 wire at the back of the fan Ecu connector block be a quick way of seeing if the fan stops spinning when pin2 has 12v? Or could I do harm by forcing it to have 12v like that?

Tracing this pin2 wire is going to be very difficult, it is wrapped up in insulation protection and disappears into the car from the engine somewhere. If I can determine the missing 12v is the problem maybe the best thing to do is give it a new 12v supply from 1 of the other wires as I described above?

[mr2magic]

Sorry, i didn't mean to sound like a dick

As to just laying a separate wire - apart from the fact that it usually looks crap and is followed by more and more other wires over time, i personally don't like the idea of driving around with a possible short circuit causing sparks or worst case a fire...ymmv.

I would work backwards. Pin 12 should have 12v but doesn't. The pin to the cluster should have 12v. Measure that at Connector A pin 5. From there if 12v is not found. You know its in the wiring between the 7.5A fuse which you checked? and the gauge cluster.

The problem we know about is that 12v is missing from pin 2..so lets solve that and see if a) the bulb lights and b) whether the fans shut off properly.

As said before..of course to check you can put 12v on the pin by laying a separate wire.....doesn't combat the root cause though.

[pbmr2]

just going to dig through my cpies of various manuals now, what year is your car?

[pbmr2]

had a dig through the manual and picked out some screen grabs, also found a load of old screen grabs from years ago.. hope these help.











bit of a random order due to the upload.

[Mr2Owner]

just going to dig through my cpies of various manuals now, what year is your car?

Cheers for all them diagrams dude, very handy to have. My car is a 94 year, it looks like them diagrams apply to it, much appreciated.

[Mr2Owner]

Sorry, i didn't mean to sound like a dick

As to just laying a separate wire - apart from the fact that it usually looks crap and is followed by more and more other wires over time, i personally don't like the idea of driving around with a possible short circuit causing sparks or worst case a fire...ymmv.

I would work backwards. Pin 12 should have 12v but doesn't. The pin to the cluster should have 12v. Measure that at Connector A pin 5. From there if 12v is not found. You know its in the wiring between the 7.5A fuse which you checked? and the gauge cluster.

The problem we know about is that 12v is missing from pin 2..so lets solve that and see if a) the bulb lights and b) whether the fans shut off properly.

As said before..of course to check you can put 12v on the pin by laying a separate wire.....doesn't combat the root cause though.

Hey mate, I wasn't thinking you sounded like a dick, quite the opposite your posts have being very helpful I think I'm slowly getting there with your help lol

I tried the following 2 tests tonight:
1 - I joined a piece of wire from pin3 to pin2 to force pin2 to have 12v I checked with a multimeter and pin 2 does now get 12v but the fan remains running.

2 - I checked for 12v at the pin5 of connector block A at the gauge as you suggested and I have no volts there, just 0.01v. (I assume connector block A is the block closest to the fan bulb area of the cluster and pin5 is from counting only the slots that have a metal pin in them from right to left. I've attached a picture of what I assumed was BlockA and the pin I took as being pin5. Did i check the correct pin?

Also, I'll just add that when I turned the key to ignition on I don't get the engine fan symbol coming on now before starting the car. It just flickered quickly on/off. However my battery wasn't able to start the car so I think this may be as a result of a flat battery, car is sitting a while at this stage. I'm leaving it charging overnight and I'll check the status of the gauge light tomorrow when I have a fully charged battery.