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sebastian manrique
sebastian manrique, Auto Mechanic
Category: Car
Satisfied Customers: 1895
Experience:  Director Ejecutivo at Multiservicios Cruz de las Mercedes
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My Audi A3 2007 radi and digital speed display do not work.

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My Audi A3 2007 radi and digital speed display do not work. The driver door wire harness had one wire open circut which i repaired
JA: Are you fixing your A3 yourself? What have you tried so far?
Customer: Yes it's a DIY job. Te radio and digital display were both working unt I had a problem with a broken wire in the harness leading from the car body into the driver door. whie investigatingthe the problem i noticed the open circuit wire but it must have rubbed onto the body of the car whie i was tugging at it as I saw a small electrical spark in the harness as I tugged it. i fxed the wire and replaced a fuse but after that the radio and the digital speedo display was blank. I removed theradio and it's fuse is ok. there are no blown fusws on the car under the bonnet and on the side of the dashboard
JA: Most vehicles have two fuse panels. Have you located both?
Customer: Yes both fuse boxes checked ok as i said above.
JA: Anything else you want the Mechanic to know before I connect you?
Customer: no thaks I think Ive give all the info

Hi, my name is Jose Sebastian, your mechanic automotive expert, and I will be happy to assist you today. I apologize for the delay to take your query


I try to be here most weekdays and some weekends. If you respond and I do not respond back right away I will do so as soon as I can.


Dear customer it is interesting to know how the short on the door was generated because it is very likely that you have more than one short in the electrical system. I would also like to know if you have made a review of the rear connections of the dash becasue it isis likely to have problems In it. I would like to know if you have not tried to follow the wiring line at the back of the dashboard to verify that you do not have any short in these wiring.

Customer: replied 11 days ago.
Hello Jose
Your job is not easy because you have to work through me and I don't have your experience and level of technical knowledge. Iam quite convinced that the problem started with an 'open circuit' in one of the wires of the harness which goes from the kick panel next to the driver's feet to the driver's door.
I should have disconnected the battery but I stupidly did not.
When I was busy trying to rejoin the broken wire it shorted against the body of the car. I saw tiny sparks and a 'sssst' sound.this resulted in a blown fuse (not sure which one) I then finished repairing the harness. Replaced the fuse. The door lock, electric window, mirrors etc were all working.
BUT, the radio did not switch on and the digital speed display did not work.
I knew that the radio has a fuse so I removed the radio and found the fuse to be OK.
NOW.......can ypu please tell me, if I remove the radio again, which wire should be 'LIVE'. I have a test light and I want to 1st see if there is power comin to the radio. IF the wireto the radio is not 'LIVE' with te ignition switched on THEN..... I will ask you where to find the other end of the Live wire. The harness related to the radio disappears behind the Dashboard and I would be pleased if you could tell me where to look for the start of this power (Live) wire.
In the meantime thank you for your patience and your help !!!
Customer: replied 11 days ago.
Please respond in writing


Dear customer, the problem is that I do not have extensive experience in this kind of equipment and unfortunately I do not have the wiring diagram to be able to tell you what the live cable is. nor what are the grounds, what I do know is that this wiring reaches the back of the board, reaching the bottom of the fuse box and from there the circuit goes directly to the battery. The good thing is that these wiring are identified by colors and you do not have to proceed to disassemble the entire branch but it is the coloration at the arrival of the equipment and then you go to the fuses and you see the coloration that you have here, the cable that matches the same color in the equipment as in the fuses is the live wire.
this is the way i use when i do not have the wiringg diagram.

Customer: replied 10 days ago.
Hi Jose
Is it possible for the Radio to be unable to switch on even if the 10 Amp fuse at the back of it is not 'Blown'?
I was told by a local mechanic that the radio contains a circuit board whch operates the Radio and the Digital Speed Indicator which is located in the small red section in the middle of the Speedo Cluster in front of the driver.. In other words..... Is it possible that if I replace the radio I will have the 2 problems solved ? (1)- The radio will function and (2) The digital display of the speed will work.

Dear customer, indeed, these equipments have an electronic/circuit board. The problem is that the circuit is interlaced. Old cars have many looms that went from component to component, now the new car circuits work in a loom know as CAN-BUS communication, this means that through a single wiring it goes through all the signals that are encoded according to the component that receives this signal.

Basically the signal that passes through the radio reaches the dashboard to the speedo, temperature indicators, warning lights, etc., if there is the possibility that when the circuit board burns, it will disable other functions below, such as the dashboard, the odometer, lights etc. According to the circuit. So, the problem may or in the wirng or in the radio, if it is the radio the prelacement will sort out the other problem as well, if it is the wiring repair should sort the problem.

Customer: replied 10 days ago.
Hi Sebastion
Thank you for your detaied response. I am going to take the chance and replace the radio, I will let you know in a week or more if it worked. Our country is in meltdown and it is difficult to get car parts at the moment. Kind regards

Yes the situation right now is not easy.
Ok dear customer, if you can you can ask in a car audio shop or garage to take a look as well, to see if it is a wiring problem that can be a cheaper fix.

In anyway, even after you rate in the 5 stars rating system we can keep in touch.
Kind regards.

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