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Silver_TT

P1675 Porsche fault code 658 - Fault - engine purge fan

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I just measured the resistance of my fan (996 624 036 04, same as your original fan?) It has 1.7 ohm, which also explains why I saw ~6A initial draw (12v/1.7 ohm = 7A). Your fan has 1.1ohm instead so initial draw is about 11A, still not 15A but getting close. Keep in mind the meter is not 100% so maybe the true resistnace is below 1.1 ohm...

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I guess I missed all the fun but good to see you're making good progress. I would consider swapping in a new fan or a known good fan because even if the measured steady current drawn of the fan is less than the fuse rating, it may still blow the fuse. The reason is the DC motor draws maximum current when it starts to spin but as it's picking up speed, it produces electricity in opposite direction, which reduces the current drawn at the steady state. If the motor somehow get stuck even momentarily, it will blow the fuse (e.g., if you hold the blades with your hand)However, check the steady current first if you can. If that exceeds the fuse rating, you found the sucker.Btw, you can actually put the same fuse in series with the motor and supply 14v or so to power up the fan and see if the fuse blows. That would be a definitive test. 14v you can get from an idling engine or your ctek.

Very good point Ahsai, thanks for sharing your knowledge.
You're welcome. It's been fun following this thread :)Btw to the OP, I think it would still be worthwhile to put a fuse in series with the fan and power it up directly from the battery/ctek. If the fuse blows, we can be sure it's the fan. All it costs is a fuse, no need to get any clamp meter.
DO NOT use the CTEK for this, its has only low current capabilities for maintaining memory settings trying to run a 15 amp circuit with it will blow the fuse in the CTEK unit........
JFP, thanks for catching that. I didn't realize we're talking about 15A since that fan looks puny to me. Ctek can supply up to 7A in supply mode though for future reference. Use the car battery with a 15A fuse in series then.I just measured my fan (996 c2) using a 12v security backup battey. It draws ~6A initially for a split second then goes to 3.5A at steady state.
A lot of people make that expensive mistake, often damaging the CTEK before the fuse lets go.
Actually the ctek has circuits to potect itself from overloading in supply mode. Way smarter than I thought. From the owner manual" In this mode, MULTI US 7002 can also be used as a power generation unit for operating equipment that requires 13.6V and a maximum of 7A. If the selected current exceeds 7A, the output voltage will drop as the load increases. The charger has electronic overload protection in this mode, which is activated if the charge is so great that the output voltage from the charger falls below around 9V and the current ís around 7A. In the event of an overload, the charger goes into error mode (lamp 0). Supply mode is indicated with lamp D and lamp 5."Is there also a physical fuse inside? I would expect so for last line of defence....maybe i will open up mine and check. The owner manual doesnt mention any fuse.

There is a fuse (3 amp if memory serves) in the line going to the load, it is not in the box itself (the box like bump in the wires):

Comfort%20Indicator%20Eyelet%20M6_0.jpg

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Ya, the only other thing I would say is that my multimeter is about as cheap as they come. I literally bought it on eBay when I was in college for like $5. Probably not the most accurate or sohpisticated.

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Assuming the Turbo pulls the same or similar amps as the C2, that's pretty low amperage. Wouldn't my $2 multimeter from FleaBay be capable of measuring this? If so, does the multimeter need to measure this while the power is already being supplied from the power source? Or is the multimeter capable of measuring this if I just contact the two leads on the multimeter to the two leads on the fan?

As far as the direct battery -> fan connection with a fuse in the middle, that makes a lot of sense and conceptually is very simple. However, it's just me at home today and I don't really know how I would do that with only 2 hands. I would have to solder the wires to the fuse or something and I can't find my soldering gun. If I show up at Auto Zone again they are going to think I'm either stealing or insane.

I forgot that Sunset parts is closed on Sundays but I am going to call then tomorrow at 10am PST to get a fan ordered. Probably will get here Wednesday if they have one already in stock. Looking around at some other places, looks like I should be able to get an OEM fan for around $75 + shipping.

Most inexpensive multimeters are not designed to handle much of a current load (this is when the current load is passing thru the meter itself), and often have an internal fuse rated at less than 1 amp to protect the meter from being burnt by too much amperage.

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Assuming the Turbo pulls the same or similar amps as the C2, that's pretty low amperage. Wouldn't my $2 multimeter from FleaBay be capable of measuring this? If so, does the multimeter need to measure this while the power is already being supplied from the power source? Or is the multimeter capable of measuring this if I just contact the two leads on the multimeter to the two leads on the fan?

As far as the direct battery -> fan connection with a fuse in the middle, that makes a lot of sense and conceptually is very simple. However, it's just me at home today and I don't really know how I would do that with only 2 hands. I would have to solder the wires to the fuse or something and I can't find my soldering gun. If I show up at Auto Zone again they are going to think I'm either stealing or insane.

I forgot that Sunset parts is closed on Sundays but I am going to call then tomorrow at 10am PST to get a fan ordered. Probably will get here Wednesday if they have one already in stock. Looking around at some other places, looks like I should be able to get an OEM fan for around $75 + shipping.

Most inexpensive multimeters are not designed to handle much of a current load (this is when the current load is passing thru the meter itself), and often have an internal fuse rated at less than 1 amp to protect the meter from being burnt by too much amperage.

For future reference, say a birthday or father's day gift, get yourself something like this Power Probe tester:

41S%2BOc8POrL._SX385_.jpg

These things cannot only test circuits for continuity and resistance, then can also deliver 12V power to run something like a fan.

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Thanks, JFP. I'll pick one up. You never need something like one of these until you need it ;)

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Because of the way they are set up, one probe can do a lot of functions, which lets one tech get a lot more accomplished unaided. Power Probe is just one brand, shop around for one that had the best set of features, or happens to be on sale.

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Ya, that's interesting, I just noticed that -- one probe tip instead of two like my multimeter has. That's interesting as I would have thought it needed to have two to test for complete continuity. For example in our continuity test we were testing from two leads, one lead to the metal housing, etc. I guess this one is able to do that all with one single probe somehow. Pretty fancy.

It's only $100 on amazon with free shipping and I have a $35 credit over there anyway I was looking to use at some point in the future so I think now is as good a time as any to pick one up. If you think this is a good one, I will spring for it. Without having used these kind of tools I generally lean on what someone like you had used and says works well. I am just a novice DIYer, a wanna-be really, not stupid enough to think I'm smarter or know better than you guys with the experience.

Edited by Silver_TT

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I guess I missed all the fun but good to see you're making good progress. I would consider swapping in a new fan or a known good fan because even if the measured steady current drawn of the fan is less than the fuse rating, it may still blow the fuse. The reason is the DC motor draws maximum current when it starts to spin but as it's picking up speed, it produces electricity in opposite direction, which reduces the current drawn at the steady state. If the motor somehow get stuck even momentarily, it will blow the fuse (e.g., if you hold the blades with your hand)However, check the steady current first if you can. If that exceeds the fuse rating, you found the sucker.Btw, you can actually put the same fuse in series with the motor and supply 14v or so to power up the fan and see if the fuse blows. That would be a definitive test. 14v you can get from an idling engine or your ctek.

Very good point Ahsai, thanks for sharing your knowledge.
You're welcome. It's been fun following this thread :)Btw to the OP, I think it would still be worthwhile to put a fuse in series with the fan and power it up directly from the battery/ctek. If the fuse blows, we can be sure it's the fan. All it costs is a fuse, no need to get any clamp meter.
DO NOT use the CTEK for this, its has only low current capabilities for maintaining memory settings trying to run a 15 amp circuit with it will blow the fuse in the CTEK unit........
JFP, thanks for catching that. I didn't realize we're talking about 15A since that fan looks puny to me. Ctek can supply up to 7A in supply mode though for future reference. Use the car battery with a 15A fuse in series then.I just measured my fan (996 c2) using a 12v security backup battey. It draws ~6A initially for a split second then goes to 3.5A at steady state.
A lot of people make that expensive mistake, often damaging the CTEK before the fuse lets go.
Actually the ctek has circuits to potect itself from overloading in supply mode. Way smarter than I thought. From the owner manual" In this mode, MULTI US 7002 can also be used as a power generation unit for operating equipment that requires 13.6V and a maximum of 7A. If the selected current exceeds 7A, the output voltage will drop as the load increases. The charger has electronic overload protection in this mode, which is activated if the charge is so great that the output voltage from the charger falls below around 9V and the current ís around 7A. In the event of an overload, the charger goes into error mode (lamp 0). Supply mode is indicated with lamp D and lamp 5."Is there also a physical fuse inside? I would expect so for last line of defence....maybe i will open up mine and check. The owner manual doesnt mention any fuse.

There is a fuse (3 amp if memory serves) in the line going to the load, it is not in the box itself (the box like bump in the wires):

Comfort%20Indicator%20Eyelet%20M6_0.jpg

Just to satisfy my own curiosity to see what's inside the US7002 ctek, I opened it up. There is a min-blade 30A fuse soldered in.

post-5282-0-52673700-1371414302_thumb.jp

post-5282-0-59632100-1371414346_thumb.jp

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Ya, that's interesting, I just noticed that -- one probe tip instead of two like my multimeter has. That's interesting as I would have thought it needed to have two to test for complete continuity. For example in our continuity test we were testing from two leads, one lead to the metal housing, etc. I guess this one is able to do that all with one single probe somehow. Pretty fancy.

It's only $100 on amazon with free shipping and I have a $35 credit over there anyway I was looking to use at some point in the future so I think now is as good a time as any to pick one up. If you think this is a good one, I will spring for it. Without having used these kind of tools I generally lean on what someone like you had used and says works well. I am just a novice DIYer, a wanna-be really, not stupid enough to think I'm smarter or know better than you guys with the experience.

The picture from JFP post #80 shows "The Hook" from Power probe inc (around $400.00) but I think the Power probe III can do the job and it is around $100.00 but I think it is not reading amperage.

Edited by jpflip

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yes, you're right jpflip! Thanks for pointing that out -- I missed that. Amazon is selling "The Hook" for $315 with free shipping. Still not bad and reading amperage would be nice to have.

I think my brain is a bit fried from having my head in the hot engine compartment of the TT for the last 24 hours :wacko:

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Ya, that's interesting, I just noticed that -- one probe tip instead of two like my multimeter has. That's interesting as I would have thought it needed to have two to test for complete continuity. For example in our continuity test we were testing from two leads, one lead to the metal housing, etc. I guess this one is able to do that all with one single probe somehow. Pretty fancy.

It's only $100 on amazon with free shipping and I have a $35 credit over there anyway I was looking to use at some point in the future so I think now is as good a time as any to pick one up. If you think this is a good one, I will spring for it. Without having used these kind of tools I generally lean on what someone like you had used and says works well. I am just a novice DIYer, a wanna-be really, not stupid enough to think I'm smarter or know better than you guys with the experience.

The picture from JFP post #80 shows "The Hook" from Power probe inc (around $400.00) but I think the Power probe III can do the job and it is around $100.00 but I think it is not reading amperage.

Very few testers can measure amperage because the internals in the meter have to be beefed up to handle the current.

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I guess I missed all the fun but good to see you're making good progress. I would consider swapping in a new fan or a known good fan because even if the measured steady current drawn of the fan is less than the fuse rating, it may still blow the fuse. The reason is the DC motor draws maximum current when it starts to spin but as it's picking up speed, it produces electricity in opposite direction, which reduces the current drawn at the steady state. If the motor somehow get stuck even momentarily, it will blow the fuse (e.g., if you hold the blades with your hand)However, check the steady current first if you can. If that exceeds the fuse rating, you found the sucker.Btw, you can actually put the same fuse in series with the motor and supply 14v or so to power up the fan and see if the fuse blows. That would be a definitive test. 14v you can get from an idling engine or your ctek.

Very good point Ahsai, thanks for sharing your knowledge.
You're welcome. It's been fun following this thread :)Btw to the OP, I think it would still be worthwhile to put a fuse in series with the fan and power it up directly from the battery/ctek. If the fuse blows, we can be sure it's the fan. All it costs is a fuse, no need to get any clamp meter.
DO NOT use the CTEK for this, its has only low current capabilities for maintaining memory settings trying to run a 15 amp circuit with it will blow the fuse in the CTEK unit........
JFP, thanks for catching that. I didn't realize we're talking about 15A since that fan looks puny to me. Ctek can supply up to 7A in supply mode though for future reference. Use the car battery with a 15A fuse in series then.I just measured my fan (996 c2) using a 12v security backup battey. It draws ~6A initially for a split second then goes to 3.5A at steady state.
A lot of people make that expensive mistake, often damaging the CTEK before the fuse lets go.
Actually the ctek has circuits to potect itself from overloading in supply mode. Way smarter than I thought. From the owner manual" In this mode, MULTI US 7002 can also be used as a power generation unit for operating equipment that requires 13.6V and a maximum of 7A. If the selected current exceeds 7A, the output voltage will drop as the load increases. The charger has electronic overload protection in this mode, which is activated if the charge is so great that the output voltage from the charger falls below around 9V and the current ís around 7A. In the event of an overload, the charger goes into error mode (lamp 0). Supply mode is indicated with lamp D and lamp 5."Is there also a physical fuse inside? I would expect so for last line of defence....maybe i will open up mine and check. The owner manual doesnt mention any fuse.

There is a fuse (3 amp if memory serves) in the line going to the load, it is not in the box itself (the box like bump in the wires):

Comfort%20Indicator%20Eyelet%20M6_0.jpg

Just to satisfy my own curiosity to see what's inside the US7002 ctek, I opened it up. There is a min-blade 30A fuse soldered in.

I figured that they also had some internal protection as well as the external fuses, CTEK is definitely one of the better maintainers out there.

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Just ordered the fan from Sunset: $74.15 + shipping. They didn't have it in stock and it's 3-4 days to ship to them -- then they will have to turn around and ship it to me. Earliest I would have it is Saturday (I hope!)....if not, then early next week. Will update this thread once the new fan is installed to let you guys know if the fuse still blows when I tell Durametric to activate the fan. Let's hope the cold front that just moved in here sticks for the week.

Thanks again guys!

Edited by Silver_TT

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Related question:

How ill advised would it be to track my car tomorrow night for maybe 6 sessions @ 25 mins each? The ambient temperature will be around 80 F. I could open the trunk between sessions to let the engine cool. Is this a bad idea until my engine compartment fan is working... or something I should be able to get away with without risking stressing the car?

Edited by Silver_TT

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Related question:

How ill advised would it be to track my car tomorrow night for maybe 6 sessions @ 25 mins each? The ambient temperature will be around 80 F. I could open the trunk between sessions to let the engine cool. Is this a bad idea until my engine compartment fan is working... or something I should be able to get away with without risking stressing the car?

I'm a bit of a "belt and suspenders" person, so I would vote to take a pass on the track time until the car is correct. Perhaps others might want to chime in on this................

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The engine fan is a purge fan so it pulls hot air out of the engine compartment. I don't see a way to do that without that fan - especially after track laps. The engine will be hottest when you come into the pits - and even if you let it idle for cool down you won't be pulling the hot air out of the engine compartment.

So I would say pass on the track time - there will other opportunities.

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Agree with the three gentlemen especially you are talking about 25 minutes sessions and the outside temperature at 80'F!!! I'm sure you will get some more track time since the summer is only starting!

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Problem was solved by replacing the engine purge fan. $90 all-in included shipping from Sunset -- who is awesome by the way: I ordered the fan (which is a special order part) on a Monday morning and it was delivered to me today, Saturday. Jesse and the others in Parts over there at Sunset are outstanding. Very much on the ball, I've done quite a bit of business with them over the years and they never let me down.

The fan part comes with the housing. Replacement is so simple I didn't even bother posting a picture of it. There are 3 bolts around the fan housing that hold it to the trunk lid. Move the light over to the new fan housing. Takes less than 5 minutes to replace. Popped in a new 15A fuse and it's holding just fine even with the blower on a few minutes after being activated with Durametric. Previously it was blowing in less than 1 second. Without an ammeter I'll never know for 100% sure, but seems highly probable the old fan I replaced was pulling significantly more load than what is spec for this device.

Good learning experience for me troubleshooting electrical issues and also learned how to access the relays. If I ever have to do anything like this again it should only take a fraction of the time now that I've done this. The fan replacement was trivial but it was the troubleshooting that was of value in this particular exercise. Hope it can help someone else in the future.

Lots of good help on this one, so numerous +1s above. Solid guidance helped me nail this which is VERY MUCH appreciated. Just in time for my girl to get back into town this afternoon and for the weather here to jump to 90s+. I tip my hat to you gentlemen. Thank you very much.

Edited by Silver_TT

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Glad you got it sorted, now go enjoy both your lady and all that HP under your right foot.........................

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Another happy ending!!!!! I am happy for you Silver!!!!

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Spare time today, it is raining in Montreal so I did a little bit of work on the car , replacing the passenger window regulator because the window was not coming down enough to clear the seal. Found the skates on the regulator carriers completely worn.... Also did a measurement of the amperage required to operate the engine compartment fan: 2.6 amps cruising speed, not at start!!! Hope this help for future reference and before you throw your fan in the garbage Silver ;-)

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Ahh, the window regulator.....not my favorite job to do on these cars. :)

Thanks for looking at the purge fan in your TT also. Just 2.6A, huh? How much more was it on start (this is when my fuse was blowing)? Doesn't that mean my simple/cheap multimeter should be able to measure it? It looked to me like my multimeter can handle up to 10A. Will I blow my multimeter if the fan is putting out 15A+ (as we have to assume it would since it was blowing a 15A fuse)? Does this need to be measured while the fan is plugged in to the wiring harness or stand-alone/unplugged (like when measuring the resistance)? I had binned the old fan, but I can grab it out of the trash if you think my multimeter can test this (we know it's the fan now, but just for "extra credit" :)).

Edited by Silver_TT

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