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You can see that plastic wheel that I'm talking about in the ebay listing. It's common for those to fail over time leaving just the metal bearing running on your belt.
...first thing I would've checked, before continuity on the sensor!
I started getting this intermittent warning this week. When I check the connector, it seems much more loose than typical cable to sensor connectors I've seen. It doesn't connect to the sensor snugly; just sort of flops around. Can someone check their connector and tell me if yours fits tightly? Before I just order a new sensor, I'd like to confirm how this connector should fit.
Also, what is the magic button to push to remove the cable connector. There seems to be some type of wire clip on top but I'm not sure if it needs to come off first.
The connector is kind of loose in the sensor housing. This is normal. You squeeze the connector metal wire catch to extract it. It comes off very easily.
Cheers,
Tore
The connector is kind of loose in the sensor housing. This is normal. You squeeze the connector metal wire catch to extract it. It comes off very easily.
Cheers,
Tore
Thanks very much. If loose is normal then it's more than likely the sensor itself. I'll just order one and be done with it.
I was able to remove the switch this afternoon. The bolt that holds it in place is 5mm.
Unlike most Porsche parts, this one is not completely sealed so I was able to take it apart. A cover is held in place by three bolts.
Using a voltmeter, I determined that when the switch is pressed in (ie. the belt is not broken, switch closed, the resistance is zero ohms). When the switch is out (ie. the belt is broken, the switch is open and has infinite resistance). The position shown in the photo would represent a broken belt and an open switch.
The problem appears to be that after 19 years of resting in one position, the metal piece in the photo that is suppose to press down on the green button has worn an indention in the plastic arm (with the wheel attached). This is not allowing the metal to press down completely on the green button. I read 26 ohms in this position. This is probably what's causing the intermittent warning. Not having a new switch to check against, I'm assuming this indention is from wear and not intentional. Regardless, it's keeping the switch from now fully closing. In fact, I could see a situation arise where the indention keeps the arm in the same position and it would never detect a broken belt. I had to physically move it from the indention to the open position.
I filled in the indention with some superglue. You can see it as the shiny spot on the plastic arm. This should allow the switch to be completely pressed in. I'll let it sit a couple days to harden then check my theory. I'll let you know if it works or not. Worse case I will order a new switch. But if a spot of super glue can save $100, so much the better.
Last edited by autobonrun; 11-12-2015 at 10:46 PM.
Reason: add info
I hope it works for you. My feeling with things like this is they've been on the vehicle for 18-20 years, It's probably best to just replace with new instead of going through the same thing a few years down the road (which usually is at the most inopportune time). Then you can forget about it for another 18+ years.
I hope it works for you. My feeling with things like this is they've been on the vehicle for 18-20 years, It's probably best to just replace with new instead of going through the same thing a few years down the road (which usually is at the most inopportune time). Then you can forget about it for another 18+ years.
Thanks. In general I agree that just replacing it is the most expeditious. But I do pick my battles. Easy 5 minute removal with a cover for internal access; the engineer in me wants to figure out how it works and why it failed. The old one had to be removed anyway; I might as well try a fix before I replace. I really think the micro-switch is just fine; just the plastic has been pressed down over the years. I want to test the theory that building the indention back up will make it good as new.
I was able to remove the switch this afternoon. The bolt that holds it in place is 5mm. Unlike most Porsche parts, this one is not completely sealed so I was able to take it apart. A cover is held in place by three bolts. Using a voltmeter, I determined that when the switch is pressed in (ie. the belt is not broken, switch closed, the resistance is zero ohms). When the switch is out (ie. the belt is broken, the switch is open and has infinite resistance). The position shown in the photo would represent a broken belt and an open switch. The problem appears to be that after 19 years of resting in one position, the metal piece in the photo that is suppose to press down on the green button has worn an indention in the plastic arm (with the wheel attached). This is not allowing the metal to press down completely on the green button. I read 26 ohms in this position. This is probably what's causing the intermittent warning. Not having a new switch to check against, I'm assuming this indention is from wear and not intentional. Regardless, it's keeping the switch from now fully closing. In fact, I could see a situation arise where the indention keeps the arm in the same position and it would never detect a broken belt. I had to physically move it from the indention to the open position. I filled in the indention with some superglue. You can see it as the shiny spot on the plastic arm. This should allow the switch to be completely pressed in. I'll let it sit a couple days to harden then check my theory. I'll let you know if it works or not. Worse case I will order a new switch. But if a spot of super glue can save $100, so much the better.
This is awesome...I am having the exact same issue...I will remove the switch and inspect it for the indentation. Thank u!
This is awesome...I am having the exact same issue...I will remove the switch and inspect it for the indentation. Thank u!
Removal and checking for the indention would be a good idea. I'm confident that the possibility exists for the switch to remain in position even if the belt were to break. The most obvious problem is when we get the intermittent warning, but the unit could very well remain in the closed position and never move to the open position because of the indention. This would be even worse than the intermittent alarm and you would never know unless you pull the unit and check. They should have used a harder plastic or metal covering on the surface to prevent the indention but I'm sure they never thought of this because this is a problem that only comes over a long period.
I checked my fix and the glue hardened enough for me to sand it down even with plastic arm. It now moves smoothly and the resistance shows 0 ohms rather than 26 ohms. I'll reinstall it tonight and see if the warning light goes out. I fully expect it to do so but with fixes you never know until it's back in place. The true test will be if it is long term fix.
Removal and checking for the indention would be a good idea. I'm confident that the possibility exists for the switch to remain in position even if the belt were to break. The most obvious problem is when we get the intermittent warning, but the unit could very well remain in the closed position and never move to the open position because of the indention. This would be even worse than the intermittent alarm and you would never know unless you pull the unit and check. They should have used a harder plastic or metal covering on the surface to prevent the indention but I'm sure they never thought of this because this is a problem that only comes over a long period. I checked my fix and the glue hardened enough for me to sand it down even with plastic arm. It now moves smoothly and the resistance shows 0 ohms rather than 26 ohms. I'll reinstall it tonight and see if the warning light goes out. I fully expect it to do so but with fixes you never know until it's back in place. The true test will be if it is long term fix.
I bent the end of the metal arm higher so that the green button would be depressed without interference from the indentation. But I am still getting a sporadic warning light. I'm afraid mine will need to be replaced.
I bent the end of the metal arm higher so that the green button would be depressed without interference from the indentation. But I am still getting a sporadic warning light. I'm afraid mine will need to be replaced.
I agree. Sounds like you need a new switch. One favor to ask, when you receive your new switch, please post back whether the arm has the indention designed in from the start.
I'm having second thoughts that the indention is there due to age and wear. When I got ready to reinstall my switch, I had to tape the arm back to allow the bolt to line up with the hole. Otherwise, the pressure of the arm on the belt kept shifting it. I'm now thinking the indention could be there to hold the arm back away from the belt to allow for ease of reinstallation.
AutoBR .. I just opened up mine to review the intermittent problem - thanks your posts above were helpful. You asked re the 'dimple' being standard or not ....
well in mine which looks original (or at least from 1993 from the date like markings on the inside - 1-12 in a circle with an arrow with what I assumed was a year in it) .... there WAS NO DIMPLE in the metal.
As per the pics below which sort of show the issue in my mind, I fixed it (well we'll see as it was intermittent and I have yet to drive for a hour or so) by taking up the slack with a think piece of hard plastic (think disposable food container) and some super glue.
here's a shot to show there doesn't seem to be a dent/indent in the bar ... I did bend the bar down slightly to check but couldn't pic that with the phone
the most wear I could see was between the surface of the wheel and the housing where the wheel runs
06-30-2015, 03:48 PM
