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Topic: Cosworth R19 Engine Run Relay/Air Con Not Working (Read 522 times) |
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manscorpio
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Cosworth R19 Engine Run Relay/Air Con Not Working
« on: Jul 4th, 2006, 11:52pm » |
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I reported a problem in March regarding massive current drain when Relay R19 is installed in Auxiliary fuse box of my 24v Estate. Removing it has enabled me to use the car and the battery has remained fully charged.
However by removing R19 the Air Con does not work - suspect that this is due to compressor clutch not engaging because it is not told that the engine is running via R19.
My question is what is causing the current drain via R19?
Any suggestions would be appreciated in this hot weather.
In the wiring diagram it appears that one output from the relay gooes to G10. Can anyone advise where this is physically located?
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sector-9
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Re: Cosworth R19 Engine Run Relay/Air Con Not Work
« Reply #1 on: Jul 4th, 2006, 11:59pm » |
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G10 sounds like an earthing point on the bodywork, which of course the relay needs to be able to operate! Do any other circuits not work with R19 removed? Specifically I'd expect heated windscreen not to assuming you have it...
Darren
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manscorpio
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Re: Cosworth R19 Engine Run Relay/Air Con Not Work
« Reply #2 on: Jul 5th, 2006, 1:27pm » |
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Darren
With R19 removed I cannot discover any other function that is affected. It only seems to affect the air-con. There is a German type of logic in not allowing the compressor to chime in unless the engine is running and I would imagine that there are other functions that could be influenced by the "engine run" relay.
The heated windows, central locking and immobiliser seem to work fine with it removed.
The reason I was asking about G10 is as a result of looking at 34-05-005 SATc 03/96 of the wiring diagram. These are a mystery to me it seems to me that K84 is a corresponds with R19, hence my question about G10.
Hope this sheds more light on the problem.
Regards
Ian
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sector-9
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Re: Cosworth R19 Engine Run Relay/Air Con Not Work
« Reply #3 on: Jul 5th, 2006, 10:38pm » |
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Well 34-04-002 shows that G10 is also used as an earth for the speedo sender on the gearbox so if the speedo works then I think G10 isn't the problem.
Even with the relay fitted, it's default position is 'off' so any circuits it feeds won't be the cause unless the relay itself is mechanically faulty and sticking in the 'on' position (which you can test easily by checking for continuity between terminals 30 and 87 on the bottom).
More likely there is a problem in the charging circuit which is discharging the battery through the relay coil (which will probably then switch the relay on and exacarbate the problem). Try checking for a voltage between the fusebox positions for terminals 85 and 86 with the engine stopped - there shouldn't be any. If there is then disconnect the alternator and check again. Do be careful to make sure the alternator wiring can't touch metal though - they're not fused and will cause a fire if they do short against earthed metalwork!
You can bypass R19 to make the air-con run by joining terminal positions 30 and 87 together on the fusebox; of course this does mean that you'll have to disconnect them when you stop the engine otherwise it could leave the compressor clutch engaged which may damage it and will also drain your battery...
Darren
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manscorpio
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Re: Cosworth R19 Engine Run Relay/Air Con Not Work
« Reply #4 on: Jul 9th, 2006, 10:47am » |
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Darren
Many thanks for your help.
I have been slow to respond until I had laid my hands on a reliable multimeter; although I had three, one has disappeared and two were sick, now fixed....
In reponse to your questions, there is no continuity beetween 30 and 87 on the bottom of the relay which suggests that it is working, yes?
Also there is no voltage between 85 and 86 in the auxiliary fuse box when the engine is off.
There must be something else that is drawing the power.
By the way I note from todays post that Paul Boulden has a very similar problem to mine, only I have not seen the erratic rev counter. His problem seems to be long term but a new alternator and battery did not cure the problem, like me.
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