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  #1  
Old 06-02-2009, 08:57 AM
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Default ECC issues - blinking REC & A/C, control unit smells fried

I have a 1993 Volvo 850 and have issues with the ECC. The problem started with blinking REC & A/C lights upon start up. Then something blew and the smell of burnt electrics entered the cabin. I replaced the MOSFET within the power stage/ blower resistor but no change. The fan works on full speed when the headlights are on regardless of the position of the fan slider. The damper motors seem to work if I adjust them with the headlights off, and then turn the fan on by turning on the head lights.

I pulled out the ECC head unit and while I couldn't find any fried components, it did smell like the white smoke that came into the cabin which coincided with loss of control of the fan and other ECC controls.

Having read plenty of threads on similar issues, I am reasonably confident that my issue is at least 1 of the following three components - the ECC control unit, the blower resistor or the blower motor. My guess is that it is the ECC control unit based on the smell. So, the questions:

1) Of these 3 components which must be specific to right hand drive (as I live in Australia)? For example, I note that the connections on the blower resistor are on the left for left hand drive cars and on the right of the resistor on my right hand drive vehicle.
2) I understand that a bad resistor could damage the blower fan. Could a bad resistor/fan damage the ECC control unit or vice versa?

Thanks for any thoughts and advice! Luke
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  #2  
Old 06-02-2009, 10:07 AM
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AS per the symptom and most commonly known issue on these vehicles, I would zero down on bad resistor. The smell from burnt resistor also comes from the vent becuase the resistor being mounted right in the air duct and I am picturing the possibility of smoke from vents briefly.
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Old 06-02-2009, 01:06 PM
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or you could look in the 850 section for the DTC testing for the ECC that i have posted ike 3-4 times in the past week or two...

if your lights are blinking you have a dtc code. should start there to see if it gives you a hint as what it might be.
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Old 06-02-2009, 02:39 PM
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+1...
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  #5  
Old 06-02-2009, 07:17 PM
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Thanks for the advice. It was recently serviced by a non-dealer Volvo specialist. Apparently the only error code that could not be cleared was 4-1-9 which relates to the power stage/blower resistor. So I pulled it out and replaced the MOFSET transistor as per the procedure followed by the Sydney chap on Brickboard. When testing, the symptoms did not change at all. So I decided that I should check the ECC head unit by pulling it out and taking it apart. The burning electrical smell was present on the head unit and not on the blower resistor, hence I don't think there was anything wrong with the blower resistor.

I re-checked the error codes myself, but the only code I could read was 1-2-1. Having read that the self-diagnostic system is not 100% reliable I am keen to investigate the ECC head unit further (even though my mechanic and I did not pull the error 4-2-0).

I will read your recent posts 850tony and see if there is anything further I can do to DTC test the ECC.

Any advice on the questions I asked about part compatibility between LHD and RHD?

Thanks for your help, I really appreciate your time. Luke
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Old 06-02-2009, 08:52 PM
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read my other post. but to sum it up make sure u are checking code with the jumper in b1. (reminds me of bingo every time haha)
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  #7  
Old 06-02-2009, 08:58 PM
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I will say most likely the ECC unit fried.
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  #8  
Old 06-02-2009, 10:13 PM
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Thanks for the assistance. It turns out I was not following the correct procedure for checking error codes. I followed Tony850's instructions more carefull and found about a dozen error codes. Code 4-2-0 was not one of them, but I am still inclined to agree with Tech that the ECC unit fried. I will post the codes later tonight to see if anyone has any further insights.

So assuming I decide to try a replacement ECC unit, do I need to get one that is designed for a right hand drive, or is the US spare part market an option for me? I'd like an answer to same question in respect of the blower resistor/power stage also as I note that the electrical connections are on the reverse side...

Thanks again, Luke.
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  #9  
Old 06-02-2009, 10:15 PM
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Oh one other question, if the blower resistor and/or blower motor are damaged, is it possible that they could cause damage to a new ECC unit? I guess I want to be sure that I don't damage a new ECC by plugging it in without replacing the blower and resistor at the same time.

Thanks.
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  #10  
Old 06-02-2009, 10:25 PM
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everything but the blower it self should be the same. wait for someone else to answer also though before u start buying stuff.

also if you threw a BUNCH of codes i would agree that its prolly your ecc...
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94' volvo 850 wagon non-turbo manual - silver
00' volvo s40 sedan turbo automatic - sliver

if the brakes didnt squeal it wouldnt be a volvo...

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Old 06-02-2009, 10:25 PM
 
 
 
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121, 1993, 850, ac, blinking, burnt, code, codes, control, ecc, error, power, stage, unit, volvo


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