Mrmerlin

If the original fuses are not corroded then it might be good to deoxit them and install them
New fuses could have slightly thinner blades and create problems

awilli6

Ok. I’ll get an eraser and go to work. Can I spray deoxite on CE panel and just let dry? I’ll clean all visible crud but do I need to do anything special with deoxite cleaning?

FredR

Ash,

Whereas I am pleased that you got the car running I fail to see how a defroster relay could cause your problem. Judging from Dr Bob's comment I suspect he is as mystified as I am.

Perhaps I can suggest that you take a photo of the CE board pointing out the relay you have identified as the defroster relay.

Clearly the LH relay was not energising so it would be useful to ensure we understand why.,.

awilli6

Ill take a pic and post today. I’m stumped also. Whatever it is, it failed once before so when I drive it, I drive it with no plans to stop anywhere.

Shark2626

Good morning! I saw your thread last week, but never imagined that it would devolve in to a No Start thread!!! I thought, Pull the amplifier and it’s done, as did probably almost everyone. But it’s so nice that you kept at it and you were able to move past the issue and get her running again. There are countless threads of s4 cars that don’t have a resolution, unfortunately.

Sometimes you just get a bad relay. Perhaps you have one in the car that’s the wrong version too. You’ll have to track it down. You’ll rebuild your confidence in the car over time. But either way I wouldn’t worry too much about it, you are more familiar with the car now and you’ll handle whatever comes up, if anything comes up.

Deoxit has several flavors. The D100 is a good one. It squirts out all over the place but don’t worry about that, it dries fairly quickly and the residual product does not conduct electricity. It enhances conductivity and it removes corrosion. Just spray it on. I wait 5 minutes to allow for some evaporation to occur and then reconnect the parts. It’s a very user friendly product.

After you finish your inspection of the CE panel and relays, and after you rebuild your confidence in the car, reinstall the amp. You had the same unit in your ‘87 and had no issues, and it seems it was not the issue with this car.

Happy Sunday!

FredR

Well look on the positive side and that is that you have a much more informed knowledge base that will doubtless prove useful in the long term and you have got the thing running with no additional spend. [as I can tell].

When reviewing the thread this morning the only point that caught my attention was the outfit who changed a relay with something they provided. I also took a look at the wiring diagrams this morning and could not spot anything obvious that fitted the profile.

In reality there any not that many elements in the problem and my approach to solving problems is invariably to work backwards and finding out what is or is not working ignition and fuel wise is the starting point. If you have spark ignition one knows the CPS, EZK, coils, HT leads and spark plugs are working and that in turn suggests a problem on the fuel side of things. Eliminate the fuel pump and the problem lies in the LH or further upstream in the relay or fuse. .

Understanding the wiring diagrams is something of an art form. They are easy to follow to some extent and then it gets to be something of a black hole. Alan's website for 928 electrics is a useful source of info and I really need to spend more time absorbing the info it contains..

awilli6

Here is a pic of the panel. The relay in question Is the one without the cover. I think 4th from left. The shop was a European repair shop. He had a relay that matched the fuel pump relay. When it still didn’t start, we switched it back.

my dash readout for the Alternator works sporadically, this morning it registered 13.5. That was with woofer and no air. With air conditioner it dropped to 12.

Shark2626

The chart says that’s a defroster relay and it’s supposed to be a 53. You can look on the bottom of it to confirm that you have a 53 in that slot, closely compare the relay diagram embossed on the bottom of it to a known (labeled) 53.

Here is your ‘89 fuse and relay chart:

http://www.928intl.com/repair/Relay/laterelay.htm

Are you reading your alternator voltage at the battery with a multimeter?

Anyway, congrats again on getting her running.

Shark2626

Just a thought... but if you bought the car from a private seller and you have his or her phone number, give them a call and ask what they had an issue with that caused them to go in to the CE panel and label the Rear Defroster and remove the cover from the other. I’m guessing they would say the defrosters but if it was something else it would be good for you to know.

Mrmerlin

https://rennlist.com/forums/attachme...relay-1989.pdf

This one may be easier to use

awilli6

I was using the chart Stan has linked. The weird thing is, I put the correct, new relay in and it wouldn’t start. I put the one w/o a cover in and voila. I’ve had the car about a year now. Did extensive work over the winter. TB/WP, motor mounts, OPG, shocks all around, steering rack, rear axle boots, brakes, rotors, tie rods, coolant reservoir, thermostat, wiring harness, tranny filter & gasket.

I’ve drove it from Memphis to get it here last year. Have driven it back once and it did great. I have to go back next month and would love to drive it but won’t if I can’t be confident in what just happened.

awilli6

I was reading the dash indicator. I’ll get a reading at the battery + post.

awilli6

One last thing. I went on eBay and bought a couple cans of R12 and the hose to put it in. The tap is too large to fit the cans. Would Home Depot have the correct hose?

Thank all of you for your continued advice, opinions and experiences with this issue. This is the longest thread I’ve ever been involved in. I’ve officially graduated with this one. The top end refresh will be this winter so stay tuned!✌️��

FredR

This surely is a mystery - doubtless there will be a reason for it. Have you tested the "new" relay for functionality? The only thing I can think of that might explain what you have experienced would be if the new relay did not work and when you stuck the old topless relay back in that was functional and that in turn triggered something else if for instance someone in the past was dicking around with the wiring for whatever reason. I could not fathom out any linkage from the wiring diagrams but that is not saying much given my hit and miss capability with the wiring diagrams..

Hopefully someone might just come up with a more credible explanation.

Shark2626

If you take Fred’s advice and try a different “new” 53, and you take mine and decipher exactly what type of relay is in there and it’s not a 53, and you still don’t have an understanding of the situation, you should probably pull the CE panel to confirm that it hasn’t been altered. It takes just a few minutes to remove it, using care on the plastic connectors at the base. I think Porsche used all grey wiring, it is on my ‘87 car, so you would probably very quickly see it new wires were added. It wouldn’t be the first if it is altered.

Or just find a couple more relays exactly like the one that works for your car, toss them in the glove box and keep happy motoring down the road, I suppose.