Hazard Switch Flasher Unit Fix
This Technical FAQ (How to...) has been carefully compiled by John Handford
My indicators stopped working coming home tonight and I had to flash the indicators manually... then it started working again! Fortunately I'd seen an excellent post recently. Feeling inspired by XTR's excellent pictures of his switch internals
http://www.tt-forum.co.uk/ttforumbbs/viewtopic.php?p=809943#809943,
I decided to take the unit apart to clean the relay contacts.
Radio and switch removal
First you need to take out the radio and then the switch. Follow this guide to remove and replace the flasher switch module: Flasher Removal
I found that my radio was difficult to remove with the Audi OEM keys. Inserting the keys sounded like they were scratching around without doing much. I have two sets and I did find that inserting two sets at once helped as it fills up the slots and is more solid. I found that the metal in the radio clip supports was bent. I straightened them with pliars and now the radio comes out easily with one set of keys.
Repair procedure:
Once you have the switch out you need to mark the top of each part with a felt pen or similar in order to get it together correctly. Carefully prise off the red cap and push out the locking bar:
Then prise up the sides of the case just under the locking bar and pull the connector. The PCB should slide out but don't force it as the LED stem will catch on things! You can see and guide it having removed the button.
There are two springs to catch so be careful not to loose them
There are two contacts for the hazard lights and one set of contacts for the indicators. The indicator contacts are shown here:
They were burnt and pitted and had welded themselves together at some stage. What happens is that the sparking causes oxides and carbon to build up and raise the contact resistance. The increased resistance causes heat and more arcing which eventually welds the contacts together. It needs to be prised apart if welded and cleaned.
A little piece of fine glass paper (not wet+dry as that's conductive) slipped between the contacts and rubbed backwards and forwards, whilst applying a little manual closing pressure, usually cleans up such contact nicely. Unfortunately there's not much room to do that. What I did manage was to poke a fine Jewlers screwdriver in between the contacts in order to scrape them clean and get back to shiney metal.
Make sure you don't bend the contacts. If you press the magnetic actuator down, the contact should close slightly before the actuator reaches its stop - that way you ensure some contact force when it closes. Make sure the contact opens with sufficient gap however. If the contacts were eaten away or you bent them too far open, the force will have lessened and you'll get poor resistance. Too small a gap and they may arc and not break contact properly. You probably won't need to clean the hazard contacts as they won't have been used much.
Give all three contact sets a spray of contact cleaner such as this Servisol Super 10. This will lubricate and keep the contact resistance low - it's remarkable stuff. You can get it from Maplins etc.
The cleaned contacts will hopefully last for a long time but it depends how badly eaten way they are. The best option would be to replace the relay. Here's a possibility but I have not checked the size - it may be too big as the Audi ones are small. It's a changeover relay but the second pole is unused in this application. http://uk.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=176587
Getting it back together is a little tricky. You need to take the sliding button apart further. Some careful prising is needed. Make sure you mark orientation of the parts. Then assemble the springs in their holes and locate them onto the pegs of the slide and click it together with the PCB assembly.
Next carefully slide the PCB assembly into the body making sure the PCB slots into the guides inside the body. It should lock into place. You can slide the locking bar back in at this stage.
You can now replace the round piece of the button slide. Make sure the single tag for the red cap is on the label side of the switch body (highlighted).
Now you can snap the red button back on and replace the unit in the car. I'm pleased to report mine works fine now |
