firemn131

hey Gang.
I have been searching for hours...
I just finished seat switches, sound proofing, rebuild window motor, hood insulation pad, lift struts, tail light socket mod, fuel lines, and wire repairs to stereo and cig lighter after mice ate them. Now got tags ready to put it on ramps to do flex plate check, and vac mod replace, and oil line replace...

So, i have checked all fuses and harness, no power to socket...Can someone help me troubleshoot this,,,,bulb control, harness routing, ordering shop man next week....

thnx..

john

JHowell37

Where in Southern MD are you located?

firemn131

I live in lusby and work at NAS PAX

Mrmerlin

first replace the fuse for the marker light and or the tail lights,
Then find the connectors for each rear side marker light they are near the corners on the floor inside the hatch each side has a 2 connector plug check these for corrosion.

Then take the tail lights apart and make sure that you have both sides filled with matching bulbs then do the same for the side markers side to side should also have the same bulbs.
then take a peek at the headlight harness under each headlight make sure the harness isnt cut where its held with the metal fastening clip under each headlamp to chassis

firemn131

I replaced all fuses and am showing power going out. No power at side marker lights, connects are clean. tail lights all match . I am not getting power to the round tail light connector either..
I will check head light harness tonight..thnx

I read on other threads about a resitor on the circuit..somewhere near the steering column..Now this was on several other types of Porsches of the same year...Does the 928 S4 have anything like that?

I really appreciate all the help!!!

john

Maleficio

Do you not have the schematics?

heinrich

most commonly, a socket has rusted off electrodes. Just trace power ... start at the output side of the fuse box and go back from there, but if you have fuse power, I almost guarantee the issue lies at or near the actual light socket.

JHowell37

You said you did a "tail light socket mod." Could you be more elaborate?

I just looked at the WSM. ALL of the bulbs in the tail light and the side marker light use the same ground (i.e. reverse, turn signal, brake, plus the tail and side marker.)

Does the turn signal work?
Does the reverse light work?
Does the brake light work? (Key has to be in and turned to the "on" position for the brake lights to work.)

If none of them work, use an ohmmeter to check for continuity between the bulb socket(s) and ground. Odds are, if NONE of them work, you have a ground issue. Chances are, it will be heavy corrosion at their ground point. Dirty grounds are not uncommon. IIRC, that ground point is located at the back corner, passenger side, behind the interior quarter panel.

firemn131

i replaced the tail light sockets that were inoperative..the light tests good on the pass side..i dont have the schematics yet, and no power on the socket..

JHowell37

I've got the wiring diagram. I'm going to put a crank sensor in mine momentarily. If that cures my issues, I may be up for a drive to Lusby.

firemn131

Sounds great!!! I am heading out of town on Thurs....Storm has me in the house so no testing tonight..I am wondering the best way to get to the output side of the fuse panel..

brake lights work and blinkers...

dr bob

Schematics will tell you which plug and pin the wiring uses to get out to the rear harnesses.

S24 is the connection at the CE panel to the bulb control unit. Green/Black wire. Connects at the bulb control to 58L on the controller at Pin 6. Out through 58L on pin 2, same colored wires in and out. The connection on pin 2 is where the wires Y to both the left tail light housing and the left corner marker light.

Fuse 40 protects the wiring for the left side. Remember that power for those lights passes through the light switch first before the fuse, and is already segregated left or right when it gets to that switch, thanks to the combo switch on the column that leaves one side parking and marker lamps on with the turn signal arm moved down and key is off. Lots of possible places for wiring to be disturbed.

Do you have +12 on the 40 fuse (both sides) with light switch on parking lights position? The fuses have little openings in the back so you can probe the fuse in place with the other meter connection grounded. If no power at the fuse there either side, you'll be going after the headlight switch and the combo switch on the column. If power on one side only, fuse is blown. If power on both sides of the fuse, you'll be looking at the bulb control unit connections next, then the harnesses and connectors from the rear apron area to the lamps and sockets. Test the fuse voltage with the combo switch centered, by the way.

firemn131

Thnks Dr. Bob...that is exactly what i needed...Going camping on thurs...so may not get to it until early next week..I will post results..can someone send me the diagram/schematic?...and also a link for the most comprhensive product vendor for the WSW and updates etc...thnx

dr bob

Get with Roger at 928srus and order the whole package (WSM's, tech pubs + on CD's) They will be at your house when you get back from the camping adventure. The scans of the wiring digrams are OK,but you'll spend some time tracing circuits between pages on many things. Fortunately the lights are all on one original sheet, scanned as two image pages. Originals are not quite 11x17/B/tabloid size, so with some careful cutting and taping you can merge two letter-size prints together into one.

Glenn M

I'm in Lex Park and could let you borrow a set of schematics and also take a look when you get back.