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Thank you for your replies, and attempted replies. Just asking for a manual to borrow for a few days. I am a former writer and understand copy right laws. Specifically needing to look at wiring for DME terminal 30 pinouts and leads and supplies. I have a fault code P1602. See my post on hunting idle made worse. Can phone or text me. 916-622-4125. Any help that doesn't get the forum members and administrators in possible trouble is welcome. Again,thanks in advance, Paul Ri-Chard
If any local members in the Roseville-Sacramento area own a 986 Bentley manual (1998 Boxster) that I can borrow over the weekend, I would really appreciate it. Need to trace a possible wiring issue that may be contributing to a P1602 (Terminal 30) and subsequent idle control valve problem. Thanks in advance, Paul Ri-Chard Roseville, California
Thanks, I will get my trustee voltmeter out on Saturday. I'll do a fresh post to see if any forum members in my area would want to loan their Bentley manuals out for the weekend.
Thanks JFP. I used my Durametric to clear the codes and left the key on the on position for 1 minute. My little base Boxster ran a little better today but consistent idle at < 800 rpms hasn't happened yet. I'll drive around a bit this week and get some miles on it to see if the P1602 code returns and/or if the idle smooths out. By the way if I have to resort to tracing the terminal 30 wiring, is there a logical way or logical pathway on how to proceed ? I looked at my DME-ECU and not even sure on how to disconnect it properly, or where terminal 30 is located on the DME-ECU. Do I disconnect my battery when removing the DME ? Thx, Paul Ri-Chard
The ICV is New, less than 40 miles, so unless the new ICV is sticking,could the code could mean something else ? Also can a disconnected battery cause it to fault to P1602 ? I was doing some work on the seats recently < 50 miles ago and disconnected the battery so I wouldn't trip the air bag light. Also maybe I didn't wait long enough for the DME to 'teach' the ICV the new values. How long is a typical adaptive 'break-in' period ? Do I need to clear the old codes first ? Before the new adaptive values can be re-learned ?
Well the idle problem is not resolved: Here are my car's 'symptoms' : When I do a cold start the car idles evenly at about 850-900 until it starts to warm up to its operating temperature. Then the idle increases to about 1140-1200rpms but never returns. I replaced the ICV with a new one... yes the part # was correct. the vacuum lines appear to be all correct except I never had a non-return check valve as the picture to the side (it ran better than it did now but with occasional stall). My Durametric gives me codes P1602 = Supply Voltage Open and P0506 = IACV control problem. Any help from the group ?
Clarification, the top photo is "before", the bottom photo is after the added bend.
Finally got the dash light to go off with top in the closed position thanks to the tip Maurice gave. Following the microswitch trouble shooting guide, there was no signal from terminal 29 ( the b-pillar microswitch). The switch has a simple two wire quick disconnect located at the base of the roll bar. Using a voltmeter, I tested the switch and it worked fine when I manually closed it. I checked the two wires going to the relay carrier. The brown one is a ground, and the brown with green stripe goes to terminal 29 on the carrier. The wire showed good continuity. . I took the switch out and compared it to my old one. What I found was that the spring was a bit weaker than my old one and was not making contact in the same position or perhaps with the same force. I put a little more bend in the spring and re-installed it and viola! No more stupid red light staring at me . this is before. I "added" about 2mm to the bend. It's pretty subtle, so take a second look at both pictures and compare. It was enough difference to close the switch ( and turn off the light) when I put it back into the car and closed the top.
Thanks Maurice, I will trouble shoot and let you know what I find out.
.Thanks the replies, I did the foam trick and the rear motor switch turns off the light only in the top down (open position), but not in the top up (closed position). In the top open position the b-pillar switch is open, right ? When closing the top, the convertible top frame meets the windshield frame exactly and snugly when the clam shell is tight and sealed even when pressing the motor for another 1-2 seconds, so I think I have the pushrods in their optimal position, however the dash light still stays on. If I lock the top down, the windows will roll up, but the dash light still stays on. Why do the the windows roll up but the dash light stay on ? Does the front microswitch have two separate signals? One that controls the windows and one that turns off the light ? The mechanism looks too simple for that. If makes more sense to me that the b-pillar microswitch is in the closed position, with the top in the nearly closed position, that the relay is now waiting for two signals: one from the closing of the clamshell, then waiting for the latch to close. If that is the case, perhaps I have a short in the b-pillar wiring or the second signal wiring in the top latch microswitch. Does any one have circuit wiring diagram that elucidates the relationship between the switches and relays ? It is amazing how one red light on your dash can make a Boxster owner nutty!!!
I had removed my clamshell and put it on a perfectly straight and level workbench.it was less than 1/2 mm out of true at all four corners. I did resort to the foam trick and now in the open (top-down) position the light goes off, however in the closed ( top-up) position the light will still not go off unless I pull the double relay. Do you think it is my b-pillar microswitch lever ?I'm thinking that the lever is making contact too late and the runtime is too short before the clamshell is tight and top fully closed. Should I try to bend it forward a bit and see if that works ?
Fred, I replaced my top too last summer on a 98 boxster. A Robbins top with the heated glass window. Mine had a similar gap, maybe 3/16". I left the car outside and the top mostly closed. I never could see daylight and the top never leaked when it rained a few times, although it rattled a bit. Suspicous, I checked the blind nuts under the top window frame where the visors and center latch bolt into. There are six total. 4 of 6 of mine were broken. I replaced all the broken ones via instructions on Mike Focke's website. That closed the gap a bit and stopped the rattle. It looks great right now. Still fussing trying to get the guide wires to fall in their tracks properly. As long as yours is watertight and the blindnuts are not broken, I would just wait it out.
Thanks JFP, I'm sure that the black GP replacement part is not compatible with my current lock assembly. The white Audi switch fits perfectly. When I was researching on-line, Pelican Parts had an alternative part Number (4B0-905-849-M56) that looks like mine.It says it works for Boxster ignition/lock assemblies 996 347 017 07 only . See link: http://www.pelicanparts.com/catalog/SuperCat/1042/POR_1042_ELIGNT_pg2.htm#item6. Says something like " Boxster (1997-04) FROM 04". Did Porsche service replace failing assemblies on the early models with '04 assemblies? I guess I should have looked at the ignition/lock assembly part number. When I was in the not-so-comfortable Houdini position I didn't want to spend another 5 seconds looking.