wds928

Chris, see if Bill Grabner needs the tools, especially the 3/4" ratchet.

LaughaC

I'm finally off the road and had a few minutes to look at my fuse box: Only one blown fuse and one fired wire on the box. It's the top wire in the big blue lower connector, 16th connector from the left.

Unfortunately, even looking at a wiring diagram, I have no clue how to identify it so I can chase it down. Any ideas?

By the way, the fuse that is blown seems to be #24, which my manual identifies as: Central Warning System Control Unit. Everytime I insert a new fuse it blows immediately, even with the ignition off, so there's clearly a short.

Note: This either either a clue, or simply more bad news: Most of the heat was closer to the passenger seat, and it toasted two bundles of wires together, (1) the bundled coming from the transmission hump which looks like power seat controler, and (2) the bundle going from the passenger trunk release box toward the fuse box. For the moment I have simply cut out the burnt sections until I can get to a store and buy a bunch of color-coded wires and replace each one. These may be important, but they are completely disconnected now so the fuse that keeps blowing is from another short.

Arghh!! I don't mind turning wrenches or tuning carburetors, but I HATE tedious electrical work, especially when it keeps a car from starting!

I guess it could be worse.

Chris
540-327-2730

Bill Ball

What year is your car again? (Helps to put that in your sig.) The block connectors are lettered (A,B,C...) left to right. The wires are then numbered with the left half top to bottom as 11-15, and the right half, 21-25. Look at the Central Electrics sheet for your car. Around the periphery of the sheet you will find the blocks indicated. Here's for 1989. The very top letter/numbers show the connection inside the fuse panel, such as a relay number and pin number on that relay. So, for example, here is block W. Wire position 22 (second one from top on right) is connected to pin 30 (battery positive current) of relay XXV. The bottom boxed codes are the sheet coordinates for the external path. So, the example goes to E87 eslewhere in the sheets. So, you are probably looking at P-11 or P-21. If I had the model year, I could tell you more.

LaughaC

Thanks. My car is an '87 S4 and the block in question is labelled "Q" at the bottom. The top right wire (red) is fried.

I'll update my signature to include year model.

dr bob

Chris--

Fuse 24 powers your interior lights.

Looking at WSM wiring diagram Page 2, for USA Lamps, find fuse 24 at coordinates G6 on the drawing. Going right and then up, follw the circuit to connection E12 (at drawing coordinates J4), so that's the multi-connector E, second from top left wire, and it should be red per the drawing. In addition, that same circuit goes out of the CE at E11, the top left wire in connector E, and it comes right back in at E23, third from top on the right side of connector E. The only reason I can think that they did this is so that pulling connector E unpowers the interior light light relay (position XXI). Anyway, that connection looped connection through connector E then goes out through T11, top left connection on connector T, from where it routes to the two rear interior lights.

Fuse 24 also supplies power to the dashboad clock, and the courtesy lamp in the glove box, through E13, third from the top on the left side of connector E.

All the external wiring from fuse 24 is red, per the drawings. Fuse 24 has no bearing on operation of the engine.

-------

Connection Q21, the red wire you describe, feeds power to the 'coolant fan amplifier', the finned black module on the RF apron under the hood. It is fed directly from the battery through a dedicated wire, and protected by fuse 28. Connection Q22, just below Q21, is the other fan lead, fuse 29, also goes to the coolant fan amplifier.

These connections are on the HVAC page 5, at drawing coordinates M35.

-----

As you work more with the diagrams, you'll notice that the drawing coordinate numbers along the sides are sequential from drawing to drawing. You can describe a drawing coordinate without mentioning the page, and you will always go to the correct point if your coordinates are accurate. With that in mind, you see little rectangles on the drawings with drawing coordinates in them showing a jump to another drawing coordinate. Find that drawing coordinate, and you'll see a little flag with your originating coordinates in it.

Alas-- the connection at connector Q21 does not affect engine operation.



HTH!

LaughaC

Thanks! You saved me some wire chasing since my first goal is to get the engine running. Now that I think about it, I did not hear the fuel pump come on. I'll try replacing that relay next time I get to do some work.

Any idea if engine operation requires the wires to be connected to the passenger hatch release box? Those got toasted, especially the red one (probably the one that goes to the front power cooling vents), and I'm haven't had time to replace that section of wiring yet. Hmm, maybe instead of splicing, I should be looking for a replacement for that portion of the harness?

Thoughts?

dr bob

Probably a good idea to do a survey of all the wiring damage, then start shopping for replacement wiring sections. 928 Int'l may or may not have them, as they are not very good sellers I suspect. Most insurance co's would total your car I suspect, so there may not be a market for them. It's worth asking, though. Some folks, like lister Rixter, may have parts cars that you could cruise through to get the parts you need. If you have the time, you'll have much more success if you do the old harness extractiuon from the donor car. Start out with a photo inventory of everything that was damaged, ship it to the possible donors, and then use it to make sure you get all the stuff you need.

The fuel pump is one of several things needed to get the engine running. See if the fuel pump relay is pulling in on crank. Then diagnose from there. Upstream to the LH/EZK, downstream to the pump. The ohm meter is your friend for downstream checks. Somebodey mentioned that they bought a signal tracer from Harbor Freight. I use a fox-n-hounds to find wires in harnesses. Good tool, but doesn't help much with wires that are short-to-ground; those are hard to trace no matter what.

Rather than going after just getting the engine sort of running, go after a whole cure. Do it all at once. If you try to piecemeal your project, you'll quickly find that damage to an ignored harness will do damage to a replacement harness you just put in.

LaughaC

Flat-bedded the car over to a mechanic. Dave knows him and thinks he can work things out. Of course the mechanic warned that the DME may be fried.

I need a wiring harness if anybody knows where I can find one.

bgrabner

I wanted to close the loop on this for those who helped me with my timing belt. 3 months later (and about 75,000 travel miles, hence the delay) I finally patched my 928 up and it fired up on THE FIRST TRY. No leaks, no funny noises, nothing (knock on wood). I am keeping a close eye on the belt, and will check the tension at 1500 miles, but i am amazed that this worked out so well. I feel much more confident about this kind of surgery on my 928's, and even more so knowing i did the work myself (with lots of extremely good guidance from Bill Sanders - major thanks to him).

Anyway, count me in as a successful TB/WP DIY'er

tomcat

Hey glad to hear it Bill.

BTW, are your moving plans certain? If so, maybe we can all get together to send you off.