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Silver_TT

P1675 Porsche fault code 658 - Fault - engine purge fan

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(sorry if I am repeating a step you already did but...) Very good troubleshooting so far. There is a possibility , your fan is pulling too much load to operate and blow the fuse. First, the blades on the fan, can it be turn easily? Did you tried to connect the fan directly to the battery. No worry about the + or - since the fan will operate in one direction or the other... Red and black wire is the positive.

Edited by jpflip

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Shoot, no dice. Removed the relay circled in red and replaced it with the relay circled in blue (and left that one with nothing). Every time I try to activate the fan using the Durametric it blows the fuse. The short must be somewhere else. How else can I track this down? Does this just leave the wiring... or, God forbid, a problrm with the DME. Electrical problems suck :)

Any ideas what I should try next? Anything else I should be doing in the relays before I put that back together?

I would remove the relay and check the wiring running to the fan, testing both wires for continuity to ground (a short). I would also consider rigging up a set of jumper wires and trying to run the fan by itself (unplugged from the harness) as jpflip is suggesting to see how the fan behaves; while nothing jumped out while checking the fan previously, it is time to see if it actually works.

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No need to apologize at all. I need all the smartest folks on this site like you andf JFP's help on this little gremlin.

To answer your question it seems that the blades of the fan can turn fairly easily, however it's kind of hard to get my hand in there because the plastic grill is impeding my ability to really reach in there. Is there any other trick?

I did not connect the fan directly to the battery. How exactly could I go about doing that?

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JFP,

1. I will remove the relay #8. When you say to check both wires for continuity, I can perform this test as I did earlier today -- but which two leads am I going to be using for the test and which specific two wires?

2. I can definitely unplug the fan again, but how exactly can i rig up a set of jumper wires to power the fan independently? For what it's worth I know it will work at least briefly for a second because I've heard it run for half a second before the fuse blows each time.

Pardon my ignorance. If it seems like I'm being anal I just want to make sure I'm really clear on these tests I'm running so I don't report back any false information to you guys and belabor this troubleshooting.

REALLY apprecaite you guys offering your time and advice !!!!!

Edited by Silver_TT

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No need to apologize at all. I need all the smartest folks on this site like you andf JFP's help on this little gremlin.

To answer your question it seems that the blades of the fan can turn fairly easily, however it's kind of hard to get my hand in there because the plastic grill is impeding my ability to really reach in there. Is there any other trick?

I did not connect the fan directly to the battery. How exactly could I go about doing that?

You need to run two wires, one to the battery + terminal, the other to a suitable chassis ground and then touch them to the fan connector to see if it quickly spins up. You can take the fan out of its current location to run this test so the wires are shorter. Just be careful with the + wire and be prepared to pull it away from the fan if the fan blades do not quickly and easily start spinning.

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JFP,

1. I will remove the relay #8. When you say to check both wires for continuity, I can perform this test as I did earlier today -- but which two leads am I going to be using for the test?

2. I can definitely unplug the fan again, but how exactly can i rig up a set of jumper wires to power the fan independently? For what it's worth I know it will work at least briefly for a second because I've heard it run for half a second before the fuse blows each time.

Pardon my ignorance. I also just want to make sure I'm really clear on these tests I'm running so I don't report back any false information to you guys and belabor this troubleshooting.

REALLY apprecaite you guys offering your time and advice !!!!!

With the fan relay out, you want to look at the resistance (you are actually reading continuity) between the terminals on the plug that goes into the fan and a suitable ground point, With the relay out, there should be no path to ground in the harness between the fan and the relay; so when you do this test, you are just looking at the wires and nothing else.

You want to spin the fan up for a bit and keep it running to see if it locks up due to a bad bearing or other internal component, which would overload the circuit and blow the fuse.

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If you got a spare 12 Volts battery not far or another car that you can bring close to the TT. With two long enough wires about 12 to 14 gauge just connect the wires directly to the fan and see if the fan start easily. Of course if the fan is at fault your wires will became hot. But we are working with 12 volts here not 220 !!! Also removing the fan from the deck is not a big job if you want to try it on your car battery.

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You need to run two wires, one to the battery + terminal, the other to a suitable chassis ground and then touch them to the fan connector to see if it quickly spins up. You can take the fan out of its current location to run this test so the wires are shorter. Just be careful with the + wire and be prepared to pull it away from the fan if the fan blades do not quickly and easily start spinning.

I can do that. One question -- I have a CTek 7002. Doesn't it have a mode where it can actually act as a battery? i wonder if I could use that??? Might be easier than removing the fan if that's possible.

If this is possible I will try this now.

post-72654-0-53705200-1371348034_thumb.j

Edited by Silver_TT

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You need to run two wires, one to the battery + terminal, the other to a suitable chassis ground and then touch them to the fan connector to see if it quickly spins up. You can take the fan out of its current location to run this test so the wires are shorter. Just be careful with the + wire and be prepared to pull it away from the fan if the fan blades do not quickly and easily start spinning.

I can do that. One question -- I have a CTek 7002. Doesn't it have a mode where it can actually act as a battery? i wonder if I could use that??? Might be easier than removing the fan if that's possible.

No, it has a setting to maintain memory settings, but that is a very low amperage supply. If the circuit is shorted, or the fan it bad, it would simply blow the fuse in the Ctek.

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:D I'm so slow to type!!!! The power for this fan is really a simple circuit. But there is a plug on the right side of the engine compartment that I would like to look at if it is clean and in proper condition. This plug also include the wires for the spoiler functions.

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:D I'm so slow to type!!!! The power for this fan is really a simple circuit. But there is a plug on the right side of the engine compartment that I would like to look at if it is clean and in proper condition. This plug also include the wires for the spoiler functions.

jpflip, are you talking about the temperature sensor? looks like a long skinny black bottle nipple? i unplugged the connector to it and it looked good on the wire side. I can post a picture if you want to see it, it's easy to pull off.

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:D I'm so slow to type!!!! The power for this fan is really a simple circuit. But there is a plug on the right side of the engine compartment that I would like to look at if it is clean and in proper condition. This plug also include the wires for the spoiler functions.

jpflip, are you talking about the temperature sensor? looks like a long skinny black bottle nipple? i unplugged the connector to it and it looked good on the wire side. I can post a picture if you want to see it, it's easy to pull off.

On the right side, if you follow the wires coming down on the right deck hinge you will see a plug with 12 wires.... Also follow the two freon hoses from the air conditioning compressor You will see the plug just above those hoses....

post-29683-0-84318300-1371349466_thumb.j

Edited by jpflip

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OK, i just bought 12 feet of lamp cord at Home Depot. Will test the fan now. Jpflip stated I don't have to worry about which is +/- so I will wire that up now and should know in a few minutes.

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I just tested the fan. It seems to spin just fine. Spins real fast and sounds right.

jpflip, let me see if I can find this plug you're talking about now. and post a picture of it.

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On post #5 you mention that you unplug the fan , installed a new fuse at B4 and select ignition but did you select the fan to work with Durametric... The fan circuit was not powered only with the ignition switch selected on, unless the engine compartment temperature was above 172...Hum....You definitively got a short somewhere.... B4 is always blowing so we got a short on the black and red wire.....If the plug in the engine compartment is clean you will have to follow the wire..... Was there anything done to the car before you had the initial fault?

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Ok, here is the plug with the 12 wires. I can understand why you wanted to look at it because it's the harness connection that connects the wires that go up into the spoiler/tail. It looks ok to me. No signs of corrosion or discoloration. See pics attached.

post-72654-0-74008600-1371352946_thumb.j

post-72654-0-78644000-1371352993_thumb.j

post-72654-0-28765700-1371353035_thumb.j

Edited by Silver_TT

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On post #5 you mention that you unplug the fan , installed a new fuse at B4 and select ignition but did you select the fan to work with Durametric... The fan circuit was not powered only with the ignition switch selected on, unless the engine compartment temperature was above 172...Hum....You definitively got a short somewhere.... B4 is always blowing so we got a short on the black and red wire.....If the plug in the engine compartment is clean you will have to follow the wire..... Was there anything done to the car before you had the initial fault?

Yes, it is B4 that is always blowing. I agree it definitely seems like there is a short somewhere... this is what I was afraid of, it seems like it's in the wiring going deep into the car. The fuse doesn't blow until I tell the car to turn on the fan using Durametric. If I don't tell it to turn on the fan, the fuse does not blow.

I had the gearbox taken out and repaired shortly after I got the vehicle, so it's possible that something could have happened while they did that??? But then again I didn't really have a ton of hours logged on the car before then. A long drive home and then a few hours after that. Maybe it's possible something happened to the wiring when they took the gearbox out, but it doesn't really seem like these wires would have anything to do with that. They also did an oil change and put on new tires.

What steps can I take now to start to narrow down where the short is?????

Edited by Silver_TT

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I see that you are already getting a lot of help. I only have two suggestions to make.

Get a smart fuse from harborfreight http://www.harborfreight.com/30-piece-self-testing-ato-atc-auto-fuse-set-67693.html

Plug it in and let the fuse blow. After that, the LED on the fuse will light up whenever the circuit is powered (when you use durametric to turn on the fan). Now you can go disconnect each segment of the cable starting from the fan end. If the LED goes out, you found the segment that is shorted.

Another way is to use a short finder http://www.amazon.com/Tool-Aid-25100-Short-Tester/dp/B000RFLR0U

then trace the cable from the source all the way to the fan to see where the short is. This needs knowledge of how the cables are routed though.

Edited by Ahsai
  • Upvote 1

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The plug in the back is a good starting point. The wires you have to look at are A11 black and red and A12 brown wire. Use your ohmmeter and check the for a ground for the black and red or A11 (ohmmeter connected between the frame and the wire)....If nil found go to the portion going to the front of the car with the relay removed and see if you got a ground again on A11 because it is the only one going to the relay. If nothing you've eliminated the aft portion of the wiring....

post-29683-0-18037300-1371388966_thumb.j

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The wire at fault has to be between the relay and the fan. Because before the relay the wire from our power source , fuse B4, is always powered. Here you got the contacting point of the relay. A3 is the black and red wire going to the engine compartment plug and to the fan...This is the wire I suspect.....For your information A2 is the signal from the ECU and A5 is the power from fuse B4....Remember, only when the relay is energized that we got a short.....

post-29683-0-89542400-1371389660_thumb.j

Edited by jpflip
  • Upvote 1

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I see that you are already getting a lot of help. I only have two suggestions to make.Get a smart fuse from harborfreight http://www.harborfreight.com/30-piece-self-testing-ato-atc-auto-fuse-set-67693.htmlPlug it in and let the fuse blow. After that, the LED on the fuse will light up whenever the circuit is powered (when you use durametric to turn on the fan). Now you can go disconnect each segment of the cable starting from the fan end. If the LED goes out, you found the segment that is shorted.Another way is to use a short finder http://www.amazon.com/Tool-Aid-25100-Short-Tester/dp/B000RFLR0Uthen trace the cable from the source all the way to the fan to see where the short is. This needs knowledge of how the cables are routed though.

Another good suggestion for you Silver !!!

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Trust me, I can use all the help I can get :) (and be very grateful for it). Thanks Ahsai, you were very helpful on my o2 sensors/cats previously.

I saw those smart fuses at AutoZone so I will go get some now. They were right above the regular fuses I bought.

jpflip - good to know that this must be between the fan and the relay. I'm assuming the connector (in the 3rd picture in my post #41 above IMG_0978.jpg) runs straight to the relay. So does this really have to be one of 3 things:

1. The fan (which it seems like it's not given our tests)

2. The wire that runs from the fan to that 12-pin connection jpflip wanted to look at last night

3. The wire from the 12-pin connection to the relay (I'm assuming there are no other segments in between, that this runs straight to the relay).

Edited by Silver_TT

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The wire at fault has to be between the relay and the fan. Because before the relay the wire from our power source , fuse B4, is always powered. Here you got the contacting point of the relay. A3 is the black and red wire going to the engine compartment plug and to the fan...This is the wire I suspect.....For your information A2 is the signal from the ECU and A5 is the power from fuse B4....Remember, only when the relay is energized that we got a short.....

Yes, I think this makes sense becuase only when I tell Durametric to turn on the engine compartment fan do I get the blown fuse. I have tried just plugging in the fuse, turning on the ignition (not > 172F in the engine), and when I pulled the fuse out again I did NOT see it blown. When I get these LED fuses that Ahsai suggested this should be even more clear to be 100% sure this is the case.

But this is very useful information to know that B4 is always powered from the power source to the relay. We must be getting close..........

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Going to AutoZone now but FYI, I put in a new fuse to B4 and turned the ignition all the way to the last point before starting the engine (so full power to all electonics). I let it sit like that for about 60 seconds and my car is not warm because it sat in the garage all night without running.

I turned off the ignition, pulled B4 and it's NOT blown. So then, jpflip, I think this confirms this is very helpful as it must mean it's between the relay and the fan then... I just wanted to do this explicit test now just in case to confirm this as it's very helpful to know it's after the relay.

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Going to AutoZone now but FYI, I put in a new fuse to B4 and turned the ignition all the way to the last point before starting the engine (so full power to all electonics). I let it sit like that for about 60 seconds and my car is not warm because it sat in the garage all night without running.

I turned off the ignition, pulled B4 and it's NOT blown. So then, jpflip, I think this confirms this is very helpful as it must mean it's between the relay and the fan then... I just wanted to do this explicit test now just in case to confirm this as it's very helpful to know it's after the relay.

Good....The ground for the fan is also a possibility (I can be wrong about my black and red wire...). The contact point for the ground (common ground for many systems) is #8 which is located on the left of the car but the exact location , I'm not sure....This is going to be our continuity check for the brown wire or connection A12....

post-29683-0-20795900-1371394064_thumb.j

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