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        General >> Problems >> Engine Bay Fan Wiring
        
(Message started by: OldTuckUnder on Sep 2^nd, 2018, 1:28pm)

Title: Engine Bay Fan Wiring
Post by OldTuckUnder on Sep 2^nd, 2018, 1:28pm

Just wrote very long thread on self inflicted wiring problem, which was too long when I tried to post, so it got lost. Will try and redo when I get time. However will cut to a resultant question in the hope that someone can give me a quick pointer.

Had engine idling for around best part of an hour yesterday whilst tracking down a problem (subject of lost posting) but at the end left engine idling for 10-15 mins, suddenly realised that temp had gone way up, but that a fan or fans were only occasionally cutting in very slowly.

Given that the problem I stated with revealed a lot of crusty wiring, I had a good look at what I think is the fan thermostat on the front of the Thermostat 2.9 Cosworth.

Not sure but at front centre top of engine there is an elbow coming out with coolant pipe to RH side of rad. Plugged in to the elbow on the right there is what I think is definitely the temp sender for the gauge, and then on the front there is another plug with two wires on what I presume is another sensor for the fans? Anyway it looks without disturbing anything that these wires are crusty with missing insulation going into the loom cover, which is bent tight and clipped back.

I haven't touched the wires (as as per lost post I don't want to touch anything until I know what its does)

So would those two wires shorted stop the fans coming on?

Is there a way to test that the fans will really work?

I have never had the car idling before for more than a few mins, the temp gauge has always been midway on normal when driving, so I have no idea if the cooling do actually work, as reading here it appears that its unusual for them to run fast when driving?

Any inputs?

Alan

Title: Re: Engine Bay Fan Wiring
Post by brds on Sep 2^nd, 2018, 2:15pm

Hi Alan, If you have an Elm327, run Forscan. It has a test for the fans. If you haven't got one then suggest you get one quick. They're cheap and Forscan is free for PCs & invaluable if you are sorting out wiring problems.
regards,
Bob

Title: Re: Engine Bay Fan Wiring
Post by Simmo on Sep 2^nd, 2018, 2:34pm

Alan. I have a similar problem on my 2.0ltr. The fans are not cutting in and randomly the gauge will shoot up. I have established that the fans are working BUT the wiring is very iffy. I have rigged a switch in the steering column shroud which is connected from the battery to one of the fans. Take my advice.... I initially wired it to run both fans BUT the wire was not heavy enough and things got a tad warm! It now runs one fan and that is sufficient so far. I could, of course, increase the wire size but I am hoping to maybe sort the job properly eventually. ;)

Title: Re: Engine Bay Fan Wiring
Post by Tompion on Sep 2^nd, 2018, 4:12pm

Mike, did you see the PM I sent you a while back.

Dave

Title: Re: Engine Bay Fan Wiring
Post by OldTuckUnder on Sep 2^nd, 2018, 6:01pm

Again everyone thanks for input.
Will see if I can just run a supply to the fans and see if both working.
Anyone know if that sensor on the front of the thermostat housing is the one that triggers fans?
As the wiring in that little piece of loom across front of engine looks brittle and as far as I can see also contains the Coil Pack wiring, for the moment I'm wondering if course of least resistance is to get an inline temp sensor, a spare relay and wire one of the fans to come on at a temp I set.
A Fan or Fans seem to come on when I turn on the AC, (is it one or both?) so may be I try and arrange leaving AC controlling one, whilst I control the other.
Alan

Title: Re: Engine Bay Fan Wiring
Post by Torbayboy on Sep 2^nd, 2018, 7:23pm

drop PJDavis a line he has extra switch on his

Title: Re: Engine Bay Fan Wiring
Post by Simmo on Sep 2^nd, 2018, 8:08pm

on 09/02/18 at 16:12:50, Tompion wrote:

Mike, did you see the PM I sent you a while back.

Dave

Thank you Dave I did see your message but I was waiting to see how the car fared in the MOT. Perhaps we could have a chat and maybe plan a visit so I can, once again, avail myself of your knowledge! I took one look at that wiring job you did on yours and nearly died of fright!
I see that the Forscan system might provide a clue as to what is wrong and if I had any idea how to use it that might help!!

I'll be in touch. Mike. ;D

Title: Re: Engine Bay Fan Wiring
Post by OldTuckUnder on Sep 2^nd, 2018, 8:31pm

Ah also meant to ask a question on the Forscan software, does it run on a Windows PC? where do I get it?
Do I need an ODB to PC cable or something cleverer to plug into the ODB port, a quick look at ELM327 devices shows they are cheap but seem to be designed to talk to Android or iOS devices which I assume that Forscan doesn't run on?
Alan

Title: Re: Engine Bay Fan Wiring
Post by Tompion on Sep 2^nd, 2018, 8:41pm

Windows version of forscan is free, other versions you pay for, details here:
https://forscan.org/download.html

I have a cheap Bluetooth elm from China works fine with my old windows laptop.

Title: Re: Engine Bay Fan Wiring
Post by Tompion on Sep 2^nd, 2018, 8:46pm

on 09/02/18 at 20:08:05, Simmo wrote:

Mike, I doubt forscan will tell you much given the symptoms you had.
I'll be out early (for me) for MOT tomorrow.

Title: Re: Engine Bay Fan Wiring
Post by PJDavis on Sep 2^nd, 2018, 9:13pm

Just disconnect the switch electrics that feed the fans on the right-side of the top of the cyl-head. I can't remember which one, (there are two switches close-by) Xander has my car so he would know. Give it about Ten seconds, and FULL fan power will come-on. The electric fans default to ON.

Title: Re: Engine Bay Fan Wiring
Post by Tompion on Sep 3^rd, 2018, 1:09am

It should always be both fans on Hi or Lo speed never just one.
As Peter said disconnecting the ECT sender should make the fans come on Hi speed after a few seconds.
Can't remember what happens if wires shorted, I would think the fans would come on for safety as the PCM (powertrain control module) doesn't know if the engine's overheating.
With the engine at lower temperatures when the AC comes on the fans will be at low speed so they'll be wired in series.
If you just use one it'll be high speed.
At higher temperatures the fans will be at high speed & wired in parallel. Probably easier to earth the controlling wires to the existing relay if you want to change the setup.
Sender location here:
http://www.fordscorpio.co.uk/manual/engineman/cosworth/24vECT.pdf

Fan wiring here:
http://www.fordscorpio.co.uk/coolfans.htm

EDIT
Just tested on my 2.3 with engine running.
Disconnected temp sensor - after a few seconds fans on low briefly before going high.
Shorted the pins - fans stayed on high.
Reconnected sensor - fans stopped immediately.

Title: Re: Engine Bay Fan Wiring
Post by Simmo on Sep 3^rd, 2018, 7:22am

Thanks Tompion. Reading that makes me realise why I shan't touch mine until you are around!! ::) ???
Good luck with the MOT. :)

Title: Re: Engine Bay Fan Wiring
Post by Tompion on Sep 3^rd, 2018, 9:25am

Cheers
Passed :), no advisories

Title: Re: Engine Bay Fan Wiring
Post by PJDavis on Sep 3^rd, 2018, 10:28am

on 09/03/18 at 09:25:54, Tompion wrote:

Cheers
Passed :), no advisories

Congratulations, another happy Scorpio.

Title: Re: Engine Bay Fan Wiring
Post by Torbayboy on Sep 3^rd, 2018, 10:56am

Great, another one carries on. (News perchance) as hidden here and we all need good news.

Roy

Title: Re: Engine Bay Fan Wiring
Post by Simmo on Sep 3^rd, 2018, 1:26pm

Roy. Details now in News, under MOT passed. ;D

Title: Re: Engine Bay Fan Wiring
Post by OldTuckUnder on Sep 3^rd, 2018, 2:29pm

Well looks like the Gods of Scorpio Crusty Wiring were on my side this morning!
First finished encasing crusty insulation to Coil Pack, TPS, VIS valve in clear silicone checking at each step that everything still appeared to be running sweetly (but that's for another topic)
So thought I'd try a step by step approach to the Fans.

First checked that the fan fuses 37,39,44 were good which they were!

Then checked to see if both fans came on slow when running cold with AC on. Both were running but are so quiet I couldn't believe at first they both were.

OK so both fans work (at least slow) and some of the wiring is OK!

How to test fast running? There is no way I'm touching the temp sensor wiring on the elbow on front of the engine! too many crusty wires in that piece of loom strapped to front of engine (well if the crinkle covering is anything to go by wiggling that piece of loom pulling the temp sensor plug has just got to cause collateral damage)

I couldn't find "Just disconnect the switch electrics that feed the fans on the right-side of the top of the cyl-head." I traced the wiring back from Temp Gauge Sensor, and Fan Temp sensor, which run back under the coil pack, I think picking up the coil pack wires as they go, then they merge with some more wires from behind RH headlamp and end in about half an in diameter loom section that terminates in a large black box (on the inside of RH front Wheel Arch) with a nut/bolt securing the top to the base from which another 1/2" dia loom bundle appears, in fact there are two of these boxes there both with big looms in/out. Maybe if I'd have had the courage I'd have undone nut/bolt and see if the two sections came apart and see if the fans cut in, but I'm not! and couldn't see any other plug along that side that might be fan related.
So Thought OK fans do work so lets just try running the engine with AC off and see if they do come on.
Start engine, after only a few mins temp gauge is reading exactly half way, smack bang on normal. I kid you not half an hour idling later the needle is in exactly the same spot and not a hint that a fan has run (how does it do that? all the other cars I have with electric fans after about 10 mins idling the electric fans would be cutting in and out keeping everything cool).
I was about to give up when I noticed the temp gauge edge up a notch, and thought just hang on, and sure enough over the next 10-15 mins the needle edged up towards the top of the white section, but still no fans! Starting to think this confirms that cooling fan circuit must be toast (as on any other car I'd be panicking by now!) The Scorpio then played Chicken with me seeing if my nerve would hold, temp gauge seemed to have stopped climbing (but no fans) Then just when I thought this is going to end in tears the needle nudged a fraction higher and bingo both fans cut in! Only ran for less than 1 min but the needle nudged down and sat for a couple of mins, before nudging up and fans cut in. Definitely faster than AC speed, but not as fast as I had expected, and each time only seemed to have to run for less that 1 min to nudge the temp down enough.
So looks like its set to keep the engine temp fairly high, but appears to be working.
So as I have never seen the gauge over half way when driving, I think this has restored my confidence to try putting a few miles on the car and enjoy it, whilst finding out what needs adding to the list of winter jobs.
Alan

Title: Re: Engine Bay Fan Wiring
Post by PJDavis on Sep 3^rd, 2018, 4:24pm

I'd be checking for a 'sticky' Thermostat. Only replace with a really good item, if you do, no QH crap! If only this site supported easy pics, (No derogatory remark intended towards the admin) I'd show you where to look for the sensor, it's a five minute job to wire-in a separate switch.

Title: Re: Engine Bay Fan Wiring
Post by Tompion on Sep 3^rd, 2018, 7:32pm

The text on this page says "The Engine Coolant Temperature (ECT) sensor (B10)"
Scroll down to the diagram & look for B10.
The black block connector you found is probably C110, the engine won't run if you disconnect it:
http://www.fordscorpio.co.uk/24vlooms.htm

Since you don't want to disturb it, if you get a scanner you can see what temperature the fans kick in - a little over 100C on the 2.3 - probably the same on yours.
With an engine cooled overnight, using the scanner you should find inlet temperature & coolant temperature are similar & much the same as ambient temp.
Assuming the coolant actually is around the boiling point of water when the fans start the above will give an indication of whether the range of the sensor is about right.

Title: Re: Engine Bay Fan Wiring
Post by Simmo on Sep 4^th, 2018, 6:24am

Be sure to check out Tompions further post in How to do things (http://www.fordscorpio.co.uk/cgi-bin/yabb/YaBB.pl?board=admin;action=display;num=1536026659) ;)

Title: Re: Engine Bay Fan Wiring
Post by OldTuckUnder on Sep 4^th, 2018, 11:16am

Hi Tompion

Thanks for "The text on this page says "The Engine Coolant Temperature (ECT) sensor (B10)"
Scroll down to the diagram & look for B10.
The black block connector you found is probably C110, the engine won't run if you disconnect it:
http://www.fordscorpio.co.uk/24vlooms.htm

That really gives me a much better picture of what goes where, and if I pluck up courage to start any engine loom wiring the likely bounds of the task.

Always amazes me what is on this site!

Alan

PS.will try the coolant test with a thermometer to ascertain temps the fans are cutting in/out

Title: Re: Engine Bay Fan Wiring
Post by OldTuckUnder on Sep 7^th, 2018, 7:45pm

Back from a 30 mile test run this afternoon thought I'd measure the temp the main fans come on go off.

So left idling, and 10 mins later when the needle hadn't moved I remembered to turn the air con off, they seem more than adequate to keep everything at a constant temp. Anyway idling like that the temp using a laser off the front elbow on the engine or the pipe from it too the rad indicated a steady 83/84 deg C.

With the air con off and increasing the idle to around 2K rpm slowly got the temp rising, and then let idle when I thought we were about there, which we were!

Now here's the strange thing the fans cut in when the elbow measured 100 deg C and cut out when it measured 110 deg C! Seems the wrong way round, repeated the cycle 3 times until I finally twigged why this seemed to be the reverse of logic. The fans are triggered to cut in at 100 which appears good, but when they cut in the fans start blowing hot air onto the front of the engine this actually increases the surface temp of the elbow where I was measuring the temp, and the regular cut out at 110 after the fans running for about a minute actually showed that the coolant had lost temp to the air via the rad. Unfortunately I don't know what that is! but anyway within a minute of the fans cutting out the surface temp of the elbow dropped back to around 98, so I think that's a fairly good indicator of what the water temp dropped to during the fan on cycle.

Anyway happy the fans are cutting in every time at 100 deg C, so I'll close this one as a non problem.
Alan