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computer codes flashing through demister light

allthis4what

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hi everyone.. ive been having some issues since i hit a pothole a few weeks ago. I dont even know where to start.. my alternator light has been on since this happened but everytime i checked my battery it was still fine,when i turn the lights on the battery light dims, the demister light has come on and will not turn off, and if i turn the demister button on sometimes the demister light and the engine light will go out.. ive replaced the alternator twice, ive changed the battery, ive replaced the fuseable link, ive checked the plug to the alternator, and last night we checked the error codes and they flashed through the demister light and had no engine light, came up with an error 55..

The tester says the alternator is fine and and now the computer says it has no errors but i havent driven the car since because it will start a few times then i will have no power again. No dash lights or anything.. the fan plug has melted a bit and it turns on within 30 seconds of starting the car and never turns off... if i turned the lights on when we checked the error codes, the codes flashed through the park brake light and everything... the dash lights arent doing the exact same thing every time either.. but the demister light will be on constantly ....i would like some thoughts on what else i may need to replace or check.. hopefully it wont be an auto electrician... thank you to anyone who may be able to make sense of this insaneness.. :)
 

Muke

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This sounds odd. Take into account I'm guessing here btw. The error codes should be the Check Engine light flashing. Code 55 is "Control unit input circuits". Putting these two together, my first investigation would be the cluster. Make sure it's all plugged in correctly, clean etc. Then if that's not it I'd check connections to the ECU. Hope it's something simple.
 

allthis4what

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so do i! well i pulled the cluster out and checked the back of it, i have one led behind the speedo that isnt working, looked at the plugs it plugs into and it all looks ok .. the only odd thing i found which may be perfectly ok i dont know .. is that there is a blue wire that has been cut off at the switch end of the dome light, the wire from the battery has been connected to a yellow wire but i have not idea where it goes or what it does.. when i bought this car the dilt who owned it had a switch under the steering wheel to turn the dome light on so i suspect that is what that wire might be but we pulled the switch out as it seemed rediculous.. im not game to reconnect the blue wires incase the yellow wire goes somewhere important.. would it be an idea to try and find out where the this mystery wire is going? i dont remember seeing that in my last vp..thanks for your reply im off to check the computer again but it seemed all fine when we did the codes..
 

bowsaw

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Sounds like that switch, being a BT1, is for turning off/on interior lights, so they can hop out and be sneaky with no light coming on, a cop feature.
 

allthis4what

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ahhhh... i never thought of that.. that is quite sneaky lol... no wonder i couldnt see the sense of of it..i dont use the dome light because it never turns off and the button just dims it when i try to turn it off.. perhaps i should join those wires back together and it might work properly... :)
 

allthis4what

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so the problem has been fixed.. thanks Muke for you advice! i replaced the ecm first which did nothing but tonight i finally got my hands on another cluster and all the lights are behaving as they should!! alternator light and demister are off etc.. the engine light is on which i will have to check but at least it is infact through the engine light and not the demister this time! Just goes to show what a pot hole can do hey!! hopefully this helps someone else out as well.. thank god it was something small! Thanks again! :)
 

Jxfwsf

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Bad contacts on the globes (aka bad earth), have had similar issues in the past with different indicator lights (think it was cel or crs illuminating slightly when the rear demister was turned on but it was so long ago I forget), clean the globe holder terminals (possibly bend them slightly so they are a tight fit and not lose) and make sure the contacts on the cluster are clean and not tarnished.... late advice but may be useful to someone else with the same issues.
 
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