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Post by Shane on Jul 18, 2017 16:55:00 GMT
Hi All!
Its been a while!
Im literally ready to get the IVA booked, thanks to dave and co (will update my build thread) apart from 1, maybe 2 issues!
The cooling fan does not turn on and the temperature gauge seems to read hot for no reason!?!?!?
The symptons:
If I turn the car on from a cold start the temp gauge creeps up to 'H' (hot) within a minute but in reality the physical radiator, pipes and water is nowhere near that hot.
At first I though it may be an air lock so I drained the system and refilled slowly while the engine was idling, no joy.
Secondly the fan never comes on.
What i have done to try and resolve this:
1. Replaced the temperature sensor at the back of the engine (by the looped cooling pipe)
2. Replaced the thermostat (although this doesn't 'sense' anything)
3. Checked the relay by applying 12v power to close the switch and then checked ohms on the other 2 pins and it was fine.
4. Connected the fan to 12v power and the fan works fine
If i 'bridge' the 2 wires that connect to the relay then fan activates, which suggests to me that something is not activating the relay to tell the fan to come one!
Another test i did was to let the car idle until it genuinely started to overheat i.e the rad and pipes were very hot and i saw the first sign of steam from the rad cap which took about 10 minutes, then I bridged the relay to engage the fan and sure enough everything cooled down and kept idling for another 10 minutes absolutely fine.
Im hoping by fixing whatever is causing the fan not to come on will also sort out the temp gauge reading.
Any and all suggestions very welcome!
Thanks
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Post by p5curly on Jul 18, 2017 17:39:03 GMT
I thought we had established that the relay was faulty when we where at curbourgh as Paul aka fatboy checked it with a multi meter
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Post by Shane on Jul 18, 2017 17:54:25 GMT
Not when I checked it mate, i took it off then added 12v to the pins to close the switch in the relay (clicking sound) and then checked the resistance with a multimeter while the switch was closed and it was fine, unless im doing something wrong?
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Post by gwnwar on Jul 18, 2017 19:37:33 GMT
The coolant fan relay get its power to the B/W wire on relay from the engine fuse 15A inside box. Do you have power there with key on??
The ground use to trigger the relay is from the PCM/ECU is the R/G wire on relay.
Do you have continuity of the R/G wire from relay to PCM connector ??
The PCM get the temp signal from the temp sensor rear of the head . Is this the one you changed?? I believe it is gray..
this sensor go to a connector up by the throttle body. it is part of the injector harness connected to the engine harness by TBody..
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Post by Shane on Jul 18, 2017 19:59:44 GMT
Thanks Gwnwar, thats given me a few things to check!
Yes thats the temp sensor thats been changed. I will if I have power going to the the relay via the B/W wire with the key one and will check the continuity.
Will update once ive done this!
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Post by Shane on Jul 19, 2017 11:27:56 GMT
Hi gwnwar I think ive figured it out, 3 wires on the relay have continuity end to end except the BLUE/YELLOW wire which goes direct to the 30A fan fuse! From looking at the diagram the wire should go from the fan relay directly to the fan fuse so from my basic understanding there must be a break in the wire somewhere as I have checked the connectors on both ends and they are good! Please tell me im on the right track! Thanks  |
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Post by Shane on Jul 19, 2017 11:39:43 GMT
This is the wiring diagram i have been using from a 1999 but ignoring the condenser fan section as I dont have it.  |
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Post by gwnwar on Jul 19, 2017 13:43:42 GMT
Yes that is the right R/G wire.
Print out is good.. B/W power to relay coil, R/G grounds relay coil, L(blue)/Y power for fan to relay, Y power from relay to fan after
R/G is grounded and pulls relay lever on..
What you also need is the signal from the temp sensor to the PCM.. That is a R/L(blue) wire from sensor to PCU.. check continuity on
that wire..
In the temp sensor connector the V/W gauge cluster temp gauge
R/L(blue)to PCU to tell PCU, eng.is hot and to send ground R/G to relay to turn fan on..
B/R is to car ground.. under dash multi wire ground strip 6 wires to one place..4B, 1B/R, 1B/L
check this connector for ground to frame and from connector to temp sensor. continuity from A>B
Hope this makes sense.It does in my head. My mind and fingers don't always work together to say what I mean.
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Post by Shane on Jul 19, 2017 13:53:27 GMT
Thanks gwnwar how you know that of the top of your head baffles me but the good news is, that was the problem! I just bypassed the BLUE/YELLOW wire and the fan came one when the engine got hot! 10 points to me The issue im facing now is the temp gauge on the dash is HOT constantly, but the fan is turning on and off while idling and them turns on again, which seems to me the 'sensors' and the fan are working correctly. Why would the temp gauge be showing HOT constantly? Baring in mind when the car is started cold is sits on COLD for a good 5 minutes then shoots up 2 HOT but the fan still doesnt come on straight away, its as if the gauge is completely wrong!? |
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Post by gwnwar on Jul 19, 2017 15:31:25 GMT
Great news on the fan working..
As for the gauge it is not a real true temp gauge it is an on/off cold/hot no in between.
Same with the oil pressure gauge it shows pressure at 0 or 5psi it swings to half way or were it feels like..
There could be a problem with the gauge or circuit board for gauge cluster..
Wiring you could check the V/W wire from sender to gauge cluster for continuity 0.00 reading unplugged both ends..
And for wire to engine for it being pinched and grounded and board for damage..
That wire goes through a connector by the throttle body 8 wire connector.. Check for good clean connection and wires not pinched and shorted to engine.. All that wire does is send a ground to gauge..
Coolant system is full and no air pockets??.. Jack front of car so radiator filler is above the engine let run till you can see flow..
Did you put in an OEM thermostat. That and rad cap are things I don't use after market..
By chance did you put plumbers tape on threads of sensor when replacing it..
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Post by Shane on Jul 19, 2017 16:09:20 GMT
My spider senses are telling me its either the thermostat not opening fully or the water pump not pumping fully. I have been testing loads and from what i can see/feel the engine gets VERY hot which does coincide with the guage but I cant see any flow in the radiator with the cap off and the bottom outlet pipe is still cold. Im getting the feeling the thermostat is not opening fully which is why i can see a little bit of steam and its taking a long time for the pipes to warm up (which they eventually do and the fan comes on) either that or the pump aint pumping fully. Also when i squeeze the rad outlet pipe i cant feel any pressure i would imagine the pipe should at least feel a little firmer? The thermostat and rad cap/radiator are new, but not OEM Should it have plumbers tape on water temp sensor? Thanks again gwnwar |
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Post by gwnwar on Jul 19, 2017 20:34:17 GMT
No Tape.. If you are going to replace the thermostat, just for now pull it out take the center section out of it and replace the ring part that will slow the flow a little and you should see flow in radiator filler.. see if it is better. Alt/WP belt is tight right..
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Post by snowbird1 on Jul 20, 2017 6:12:58 GMT
Check that you are getting flow through the little 8 mm pipe from the rear of the cylinder head, it was blocked on mine.
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Post by Shane on Jul 20, 2017 7:47:05 GMT
Check that you are getting flow through the little 8 mm pipe from the rear of the cylinder head, it was blocked on mine. Thanks mate, sounds like a stupid question but how can you check if there is flow? Cheers |
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Post by Shane on Jul 20, 2017 12:46:15 GMT
Update: Ive checked continuity on temp sensor, VIOLET/WHITE from sensor to cluster, RED/BLUE to PCM both were fine, according to my wiring diagram the BLACK/RED goes to PCM which was fine and to the heated oxyden sensor, but in all honesty I gave up looking for it so thats the only wire i havnt checked. I have taken the thermostat out and placed it in water on the hob and it opened just before it started to boil, so all good there! I am getting pressure in the pipes when the thermostat is open, the fan is coming on and going off and on again while idling, so im starting to think the car is not actually over heating and the fan, stat, rad etc is working as expected. I think the issue is the actual gauge, its reading hot after a cold start and idling for a minute or two, and nothing brings it down. Whats wrong with the bloody thing |
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