cobalt

Damn Randy.

Looking good!!!!!

Bill Ball

My electrical skills are legendary...legendarily bad, that is. But armed with a cheap multimeter and some luck, you can find the source of the curent draw. The fact that your cig lighter doesn't work is suspicious - someone has been mucking around in there. Bad aftermarket alarm or radio installs are a common problem. Anyway, you can use the fuse pull technique to locate the circuit involved most of the time and go from there. Sometimes it is more elusive, outside of the Central Electric panel, but there are electrical whizzes here that will help you find anything.

Also, it would be good to reveal your location, if you haven't already. Local support for 928s is available almost anywhere, and it helps to connect with other owners in your area.

Bill Ball

Wow. Nice wheel thread started here.

Vilhuer

TechArt website offers 7.5x17 ET52 and 9.0x17 ET47 for old models. Their 18" wheels have too small ET in my option. Best available version is 8.5 ET50.

http://www.techart.de/homee_gesamt.htm

docmirror

Trickle charger. I'm not a fan of ebay too often, but it does have some uses.

http://cgi.ebay.com/ebaymotors/12-VO...QQcmdZViewItem

Let's resolve your drain though and make sure you're not killing the battery.

Doc

JPTL

Agreed. That's the easiest & most obvious, but not the best place to tap into a hot, beefy line and a ground. You may find a wiretap on one or both of the wires going to the lighter indicating that the p.o. had an aftermarket accessory that got its power from the cig. lighter circuit.
If your fuse checks out okay (hopefully it does, because it's a high amp circuit), then I'd check the ashtray assembly connection.
IIRC, there's a spade connection that powers up the micro light next to your cig. lighter. (I can't remember, but it may power up the lighter as well.) It's easy to forget to connect that back up when pulling out the ashtray assembly. Your inoperable light and/or cig. lighter may just be the spade clip not being connected to the ashtray assembly.
Bill, when you say that there should be no more than a 60ma draw on the system, is that with the doors locked/alarm active?
The reason that I ask, is I recall reading a thread a few years back that claimed that locking the doors/activating the alarm will draw down a healthy battery within only a couple to three weeks.
I also remember a claim that turning off the car but not removing the key (i.e. leaving the key in, ignition off, column in unlocked mode) doesn't completely shut off some circuitry, and can lead to a higher than normal draw.
I've never tested this, but I just opted to believe it and I remove my key, don't lock my car (it's in the garage) and keep a battery maintainer on it - particularly during the cold, non-driving winter weather.

cobalt

The TSB I have says no more than a 90 ma draw, is 60 correct?

Alan

Actually - if everything is working correctly a stock GTS should have a current draw of <20mA with the door locked and alarm active.

I think the 60mA should be considered a threshold above which you will likely experience issues if you don't drive the car weekly - probably a point at which dealers would suggest you have the root cause debugged (if you've added aftermarket equipment) and where they migtht have had to debug if you didn't and were still in warranty... but 60mA is really too high (almost 0.75W!)

My car with many (really many) additional things installed is at about 13mA parasitic draw... I don't see any reason <20mA shouldn't be doable...

You are right about leaving the key in (bad for several reasons!), and it will indeed be slightly lower when not locked (LED's mainly - so should be very small)...

Your choice of audio headunit, amps, phone system etc affects it slightly but most modern stuff is very low leakage...

Alan

Bill Ball

Regarding the parasitic draw...I am saying with the alarm not armed. That's the way I park my car at home. I have not measured it with the alarm armed. Also, the number is somewhat approximate. 90 should be fine, but I have not seen it that high.

If retter is parking with the alarm armed for more than a week or so, the trickle charger may be needed after all. I don't know offhand how much current the alarm draws. [EDIT: I see Alan answered that. My car draws about 40ma unalarmed but that includes an aftermarket radio with LED alarm and aftermarket remote door opener. The 60ma limit I quoted came from a source I can't recall at the moment. At 40ma, Alan leads me to believe I may have some excess draw I need to track down, although I drive the car so often it's not an issue. Still, it would be instructive for me to pull some fuses and see if I can locate the draw. THANKS, ALAN!]

retter1126

Thanks for all the info guys. Sorry, I was out all day.

I did stop by the local dealer. They helped get the radio code so that's working. I asked while there what the next scheduled service. They told me there's a 90k service that I should expect to pay around $2,300. As this car is new to me and I don't know the service history, are there any thoughts? Willhoit did suggest Bob Hindson Racing in K.C. That may be a better bet to check the car out?

As for the power drain...what I'm hearing is that some say it's a natural part of the car while others say it shouldn't happen. I've stopped setting the security system as it is garaged. It is driven two or three times a week. For the possibility of wire taps, I do remember older photos of the car which show a phone that's not in the car now. I also know that the car has at least a third stereo in it as I have two previous codes that aren't for the current one.

Having said all of that, exactly what meters will I need? What kind of cost? Knowing nothing about electronics can I do the testing myself with your guidence? Will I mess it up more?

I'll be checking in off and on today. As always, much appreciated!

SteveG

There is something about taking readings with a meter that is like playing with matches except you probably won't set anyting on fire. I don't think you can damage the car thru misuse of the meter by itself. You do need to be careful with any wires or stray movements around any electricals. I fried an expensive thermostat on a simple kitchen stove b/c I didn't remove power first. Stupid. IIRC you can get a digital meter that measures milli amps and/or volts for under $20. Most good meters have protective circuits or fuses built in. Fluke makes quality meters, Lowes or Home Depot has a pretty good selection. Search here for threads on batt drain and how to trouble shoot, and hooking to ground strap in series.

docmirror

Retter, the most useful, and functional tool you will need for the 928 is a suitable DMM(digital multimeter). It must have DC Volts, resistance, and DC Amps with a 10 amp and 2 amp range. They can be bought at Harbor Freight, Northern Tools or most auto outlets. It should have three full digits and a '1' digit at the far left. This is called a 'three point five digit' meter. Fluke is the best, but also the most costly, and kind of overkill for this job. A fair meter will cost around $20-50. You will also need two small vise grip pliers, or other suitable locking pliers.

You can do the work, and if you follow instructions it won't do more damage. Important things to remember - it's all low voltage, no chance of shock unless you have an open break in the skin, and stick a probe with 12V into it. Red is plus, black is minus. Most meters are auto ranging and auto polarity.

Measuring the resting current drain is a bit tricky, because you need to maintain the connection while running the load through the DMM on amp scale. Proceed as follows:

1. Open the doors and hatch and locate all the courtesy lights. One in each door and two overhead with one at the rear trunk below the latch. Turn them all off with the doors open.

2. At the hatch, locate the tool cover and turn the two black dials 90 degrees, remove as set aside the tool cover. Locate the ground strap, coming out of the hatch floor cover, bronze color, about 20mm wide held down with a 13mm bolt, just to the left of the center hatch latch mechanism.

3. Put the DMM leads in the 10 amp range to start. Here's the tricky part; Attach one of the meter leads to a ground, possibly on the hatch latch bolt using the vise grip plier. It must be an unpainted grounding point on the chassis. Next, attach the other meter lead to the flexible part of the ground strap using the other small vise grip, just inside the strap solid plate area. It cannot be on the bolt, because the bolt is coming out.

4. Close the doors but do not lock. In the following steps do NOT turn on any accessories, turn the key on, start the car or push on the brake pedal.

5. Turn on the DMM, to 10 amp range(sometimes a separate special range on the DMM). Remove the 13mm ground lug bolt and isolate the ground lug, attached meter lead, and vise grip from the chassis using a piece of cloth or rag. all the ground current is now going through the pliers ground point, then the meter, then the other meter lead, then the ground strap and to the battery. This is called a 'make before break' circuit. We don't want to interrupt the ground circuit at any time.

6. Set the DMM on the hatch floor so it is visible when you close the hatch. Close the hatch, do not lock the car, or arm the alarm etc. Wait 1 minute.

7. Read the current on the meter. If it is below 2 amps(1.999 on the meter scale), then open the hatch, replace the bolt in the ground strap and tighten, and move the meter lead to the 2 amp position.

8. Remove the ground strap bolt again, and isolate the ground strap from the chassis. You are now reading the current draw from 0 to 1.999 amps. Close the hatch and wait for 1 minute.

9. This value is your unloaded curent drain. The only thing that should be on now is the radio anti-theft sense and it should be below 10mA (ten thousands of an amp) or .010-ish on the meter.

10. Lock the car, arming the vehicle anti-theft. Wait one minute. Read the meter. This is your total resting current drain. I would think it should be below 25mA (.025 on the meter). If it's above 50 that is bad, above 100 and it's very bad.

11. Unlock the car, open the hatch, replace the bolt on the ground strap and tighten.

12. Remove the vise-grip pliers and the meter. Turn all your courtesy lights to the door-activated position.

Here's a suitable meter:

http://cgi.ebay.com/Mastech-9-Functi...QQcmdZViewItem

Let us know how you get on.
Doc

Bill Ball

Ask them what's include in the 90K service. Porsche's schedule for the timing belt is every 45K miles, so I would expect it at 90K, and a timing belt would account for a lot of this charge. You want a shop that has plenty of experience and a good reputation for taking care of 928s specifically, and that is quite often NOT the case with Porsche dealers. Some will even admit they have not taken care of 928s in a while. More routinely the service every 30-45K miles would include:
- spark plugs. Wires, cap and rotors at some point, and they are expensive (over $400)
- brakes - at least pads and likely rotors unless they were done off schedule; fluid flush
- Coolant change
- At 90K you might get all accessory belts and hoses, especially if you do not have a record of them being changed
- tranny fluid an filter change; differential as well unless done at 60K
- fuel filter
- oil change and filter
- air filter
- air pump filter

It's not normal. Alan in the best electrical reference source, and you saw what he said. You can get an inexpensive multimeter at RadioShack. I guess no one has done a step-by-step illustrated guide on how to do this, but it's not hard or dangerous. If the excess draw is in a circuit that is fused by the CE panel, the process can be real easy. Hook up the meter across the ground strap, set it to measure millamps, detach the ground strap so the meter now becomes the ground path. Close everything up and wait for the lights to go off. Before the lights go off, it could draw an amp (1000ma) or so. And if the car has been run in the last 45 minutes, there is a fan circuit that can still be active. But after the lights go out on a car that has sat unstarted for a while, the draw should drop to the residual level. If it is high, open the passenger door and wedge something against the door pin and wait uintil the lights go out again. Expose the CE panel under the passenger side front carpet, under a flip up plywood panel. You're in for a treat if you haven't seen one of these before. I've never seen anything like it on another car. Anyway, there is a row of about 45 fuses in blocks of 5 across the top. Start pulling them and watch the ammeter reading. If you find a fuse or two that account for the excessive draw, we can take it from there. If after pulling all the fuses, all or most of the excessive draw is still there, then it gets more interesting.

If you drive the car every 2-3 days, you should never have a problem. If there is so much drain that the battery discharges in that short of a period, you have a honkin' parasitic drain.

retter1126

Thanks for the details all. And thanks Bill and Doc for the detail. Although I've had to get back to the biz for a few new projects I'm frustrated enough with the problem to start looking into it. Here are the current events my new understanding...

I put the new battery in as you know – last Tuesday. I drove it Wednesday and Friday. It's been parked otherwise without activing the alarm. I noticed on the way home last night that the light on the stereo is flashing again as it did the last time when the battery was getting drained. I also was getting an intermitant tail lamp failure on the dash – I couldn't see that there were any problems though as they were on and the brake lights worked.

These are my thoughts...I bought the car on new years weekend. It has been parked for the most part without trouble until about three weeks ago when I decided to check the wiring on the cig lighter. I undid the two screws, pulled the ashtray, looked at the wiring, pushed the tray back in, and that's where the trouble started. I've realized that there was no trouble before pulling the ashtray.

I do appreciate the thoughts. I'm just trying to balance time on the car with keeping the business afloat so it's taking a while to get to it.

Ryan

JWise

Thanks Bill, Alan, Doc, all, for what has turned into a GREAT electrical draw diagnosis thread. Ryan, you may want to edit your thread title to reflect this.

Somewhere in the archives, there's also a great annual maintenance list by Wally Plumley of 928 Specialists. It covers many electrical items. I'll see if I can find it, and will edit this post later to add the link.



OK guys, Wally's annual maintenance list in in this thread:

https://rennlist.com/forums/showthre...al+maintenance