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Forums › The Car › 206 Problems › 206 Cooling Issue |
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 Posted: Sun Apr 10, 2016 2:38 pm |
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Joined: Apr 10, 2016
Posts: 6
Trade Rating: 0
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It's my first post here, so first of all, Hello!
As the title says, I'm one of the lucky few who has the joy of a low speed fan failure. The needle hovers at 90, then jumps up to the top before the full speed fan kicks in.
A bit of background:
Relays are both working & I purchased a second loom as a donor for another pair. All were tested from a 12v feed and produced the lovely mechanical click.
The wiring was all corroded on the bottom as per usual, so we reconnected the wiring, tidied it all up and expected that to be the fix.
No dice.
The high speed fan works a dream, but the low speed is seemingly not receiving a trigger signal to switch the relay.
We've checked circuit resistance & my colleagues (both electrical engineers) assure me the resistor in the base of the unit is functioning as when we bridge the connection, hey presto we get movement.
We're at a bit of a loss now, the last thing I can think of is the sensor in the engine water jacket, as when we unplug this, the low speed fan kicks like it's supposed to, though the car isn't throwing any error codes (unless I unplug said sensor).
Finally, the thermostat is working fine and we're pretty confident the loom is in good condition after clearing out oxidisation.
Our last ditch effort would be to install a "custom cooling loop" using some electronic wizardry.
Cheers and I look forward to some replies.
Kris
Edit - Forgot to add, 1.4 52 plate, air con model!
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Posted: Sun Apr 10, 2016 3:14 pm |
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Joined: Apr 14, 2010
Posts: 713
Trade Rating: +2
Location: Gothenburg, Sweden
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| krisfx wrote: |
The high speed fan works a dream, but the low speed is seemingly not receiving a trigger signal to switch the relay.
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Going by the diagram (3) It looks like that the low speed relay is controlled both by electronics in the engine bay fusebox and the ECU, while the high speed relay is controlled only by the ECU well, and switched +12V)There's also s wire between the ECU and fusebox involved in getting +12V to the low speed fan relay coil via a relay in the fusebox...
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| Silvermetallic 2004 206 RC | |
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Posted: Sun Apr 10, 2016 3:22 pm |
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Joined: Apr 10, 2016
Posts: 6
Trade Rating: 0
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| mtempsch wrote: |
| krisfx wrote: |
The high speed fan works a dream, but the low speed is seemingly not receiving a trigger signal to switch the relay.
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Going by the diagram (3) It looks like that the low speed relay is controlled both by electronics in the engine bay fusebox and the ECU, while the high speed relay is controlled only by the ECU well, and switched +12V)There's also s wire between the ECU and fusebox involved in getting +12V to the low speed fan relay coil via a relay in the fusebox... |
It seems strange that this part of the loom receives power, but doesn't receive the "switch" signal when the time is right. Arguably that wire may be worth looking for, sounds daft, but where should I be looking for it in the engine bay, a lot of the cooling stuff is quite tucked.
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Posted: Sun Apr 10, 2016 4:12 pm |
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Joined: Apr 14, 2010
Posts: 713
Trade Rating: +2
Location: Gothenburg, Sweden
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| krisfx wrote: |
| Arguably that wire may be worth looking for, sounds daft, but where should I be looking for it in the engine bay, a lot of the cooling stuff is quite tucked. |
The one between ECU and fusebox? The connectors at either end would be my targets - colour of connector and numbers of pins are given in the diagram, as well as cable numbers and which pin in the connector.
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| Silvermetallic 2004 206 RC | |
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Posted: Sun Apr 10, 2016 4:37 pm |
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Joined: Apr 10, 2016
Posts: 6
Trade Rating: 0
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| mtempsch wrote: |
| krisfx wrote: |
| Arguably that wire may be worth looking for, sounds daft, but where should I be looking for it in the engine bay, a lot of the cooling stuff is quite tucked. |
The one between ECU and fusebox? The connectors at either end would be my targets - colour of connector and numbers of pins are given in the diagram, as well as cable numbers and which pin in the connector. |
Yes, that one. We're confident that the wiring (12V power) is good on the relay side and we're basically missing the trigger signal that switches the relay from open to closed. So I think looking for the wires between the ECU and the fusebox is a good idea.
Another possibility is that these trigger wires (white and blue I believe) are broken along the loom, but then, the fan is triggered when the temp sensor is disconnected, suggesting that this isn't the case.
Edit: With the sensor unplugged, I think the high speed triggers, which opens up a few other possibilities!
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Posted: Mon Apr 11, 2016 5:17 am |
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Joined: Apr 10, 2016
Posts: 6
Trade Rating: 0
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Hi guys,update.
I've had the electronics lads look a the wiring diagram that you provided, we're thinking that we've got a potential issue with the fuse box relay/somewhere on this side, is there a way to access this relay? We're going to clean out the connection to the fuse box regardless.
Cheers for your help.
Kris
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Posted: Tue Apr 12, 2016 1:03 pm |
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Joined: Apr 10, 2016
Posts: 6
Trade Rating: 0
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Okay, so we traced wires back to the fusebox and ECU with no issues and no resolution.
Basically, we think the ecu is "forgetting" to turn on the fan at 90 and as it's my first car, which I don't plan on keeping much longer, we're just going to wire in an ignition live switch, which I can use to manually control the fan.
The only other option is replacing the ECU and I'll be f****d if I do that.
Thanks for all the help, hopefully some of the information I've given/received will help others.
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Posted: Sun May 15, 2016 4:22 pm |
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Joined: Apr 10, 2016
Posts: 6
Trade Rating: 0
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Sorry to revive an old thread, but for those who get stuck in a similar position where they diagnosed the following as okay:
- Relays
- Resistor
- Wiring
We capped off the feed that comes and goes from the ECU on the low speed relay and replaced that wire with a new section of automotive wire to withstand engine bay temps. After this, we fed the wire through the firewall (much like amp wire) and then to a new switch on the dashboard just behind the indicator stalk, which handily has a 1:30 shut off from the car supply if left turned on without ignition.
In all it cost me about £20-30 to sort, though if I'd had to pay for the two other engineers who spent a few weekends diagnosing it, I think I'd be bankrupt.
I know it's like pulling teeth seeing this, but if it helps someone else out in a similar position it's probably worth having around as there was literally no help for me other than tried methods!
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