Will any na s5 ECU work in my 91 Convertable or must it me from a vert?
 

My vert has had a lot of water in it and so my ECU has water damage alot of water damage and it is in the shop right now and the guy said that my ECU my be to far gone to save if it dont dry out well tonight... so I just wanted to know if I can get any S5 na ecu or dose it have to be from a Vert only. Any way I hope this is all my car needs to be running good once more.

Thanks
Zane

The S5 ecu will work as long as its the same transmission ecu

ECUs aren't transmission specific. Any S5 NA ECU will work (N350, 351, 352, 353...).

Though the above posts are true, there is one thing you will have to watch out for.

The two computers I have personally run into problems with in my s5 vert that are NOT as general as s5 and s4 are

- the body computer (located near the fuse box on the driver side kickpanel)

and

- the Airbag computers and redundant power supply (located directly underneath the steering column near the fuel pump relay)

(not sure of the exact location because mine was ductaped under there due to a previous owner)



The airbag computer i have failed to find new, but haven't really tried because its just not practical for me to keep it.

The body computer you can find on mazdatrix, but bear in mind that it houses the flasher as well, which may or may not be different (i'm not sure)

I replaced my burnt 49 state S5 vert ecu with a 90 california coupe ecu. (don't remember the ecu numbers) It works & runs fine. I do have a warning panel light that flashes-the seat belt. :dunno: Specifically, the seatbelt beeper and light flash if the seatbelt is not fastened; if the seat belt is fastened, the beeper stops but the light still flashes. I think this is due to the mousebelt coupe vs. the airbag vert.

had exactly the same problem.. my vert's prior owner left it open through a two day rain..
regardless..
all of my electronics are N350
and I've got a N353 ecu under the panel now. Runs great.

you're in the clear man

That's odd. According to the S5 wiring diagrams, the seatbelt warning should be strictly CPU controlled, not ECU. The "passive belts" (mouse belts) and air bag diagrams just show CPU connections as well.

I can't tell if that diagram is for the without airbag (89 vert) with airbag (90+vert) because they are different systems.


That said, I agree you may be right. Replacing the ECU was the exact moment the seatbelt light started the flash. It was guilt by association and I had really not looked at the wiring diagrams till you pointed it out. Pretty intellectually lazy of me.:rolleyes:

Maybe the CPU is at fault. I hate the FC66...

The only other thing I can think of is that the diagrams I posted are technically for a '91 (from here: http://foxed.ca/foxed/index.php?page...nual#secondgen). I've never seen any other year available for S5s. But if you skim through it all, it seems they did a pretty thorough job outlining the differences between coupe and vert at least. Certainly more in depth than the S4 wiring diagrams.

You might just track down the wire for the seatbelt warning light and cut it. You'd at least be rid of the flashing light, and I'm sure you can handle remembering to buckle up :).

I considered clipping the wire, but I hate to hack my car to solve a problem.

However with a new development, I am now on a quest. My headlight dimmer has been semi-functional for the last couple of safety inspections. I have gone through several used FC66 CPU's, they usually die pretty quick. Icemark (rip) had stopped fixing the FC66 because they were terribly unreliable especially when rebuilt. He advised me to buy the new board ($85) from mazdatrix. :icon_no2:

Today, my Safety Inspector's Father (son runs a branch repair facility, dad runs the main facility) was in the shop to visit and he vetoed passing me with a non-functioning dimmer. Basically the dimmer flashes to highbeam but immediately switches back to low beam. The relay in the latch circuit is bad-it won't hold.

Then the Dad noticed that the highbeam flashed up and down-in time with the 'fasten seatbelt' light! Holy crap! It is the CPU!

I'm done with the unreliable FC66 CPU relay latch circuit. All it basically does is duplicates the function of a push-on/push-off SPST switch by taking the signal to ground! I am doing this my way now. If you look at the circuit, the light and the beeper operate independently. Experience bears that out since the beeper beeps in time with the light if the seatbelts are not fastened but stops beeping when the seatbelts are fastened. IOW, I could clip the wire to the light and reattach it to the same circuit as the beeper, therefore preserving the stock operation of the light/beeper but preventing that light from flashing except when I actually don't fasten my seat belt. It isn't a hack of the operation is indistinguishable from factory. :)

Hey guys thanks for the good news.

No problem.

Well that doesn't sound like too much more work than just clipping the seatbelt warning light wire and leaving it.

I myself have the entire speaker removed from my CPU. The seatbelt sensors didn't work properly when I bought the car, so the annoying beep would never stop. So I popped open the CPU and clipped the speaker right off the board. This was 9 years ago, and I might do things differently today, but I don't really miss the beeping. From the sound of it, that sort of thing might kill you, so I'd advise your planned route intsead.

Sorry to bump this thread, but can I for sure use a N350 ecu in place of my N353 ecu? My omp fried mine.

A S5 NA ECU is a S5 ECU... So yes it should work just fine.