S4 relay information - HUGE FAVOR

9757 Views 46 Replies 9 Participants Last post by ddouglas77, Oct 10, 2007

the_sicilian

Discussion Starter · Oct 1, 2007

guys i need some info.

heres the deal. my 1990 (S3 motronic) spider keeps overheating when under heavy stress (hot air, hot sun, black spider, air-conditioning running) and i everytime its the 30amp fuse on the engine-fan relay that is sizzling hot (the whole relay) and the fuse is slightly melted on one side even though the fuse isnt blown.

right. so my usual fix of throwing money at the problem, is to replace the relay. but methinks that perhaps the problem is that some americano mechanic perhaps thought he was smarter than the owner, and read the 1989 body-tag and ignored the 1990 model year tag in the hood and put the wrong relay for that specification.

i have a vendor that will replace most relays if you have the information (mfr name ie: "Sepia", "Bosch" and serial number or any info). im interested in what Series4 have there as well. interested in how they resolved the issue.

can someone with a good stock Motronic please give me the info for me to compare? (this is the second relay from the left driver-side) describe it visually to me as well if you dont mind. mine is grey.

can this also possibly be due to a bad ground-strap or something? my mechanic says it was a known issue with this year. DDouglas, did u have this issue? what does your fuse say?

thanks guys. i will owe u one. (and a sicilian owing you a favor can be a good thing)

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the_sicilian

Discussion Starter · #2 · Oct 1, 2007

the tech bulletins list a part number: AR 0082451829

ddouglas77

· #3 · Oct 1, 2007

the_sicilian said:
DDouglas, did u have this issue? what does your fuse say?

I don't, my PO hard wired the relay to be constantly running the fans. I'll check the numbers on it in the day time, can't see much out there right now.

msiert

· #4 · Oct 1, 2007 (Edited)

the_sicilian said:
im interested in what Series4 have there as well. interested in how they resolved the issue.

I'll check mine and take a picture of it tomorrow for you.

ocduff

· #5 · Oct 1, 2007

Guido -

Mine is a whitish gray with the 30 amp fuse in it, I believe. I don't have the part number in front of me, nor the part itself. It should be the same as the one for the radio, no? I believe the radio had a 10 amp fuse. Swap the realys and fuses and their locations.

It's possible it could be a relay - but you may want to start looking for other culprits as well, while in the meantime, patiently wait for us to give you a part number!!

the_sicilian

Discussion Starter · #6 · Oct 1, 2007

thanks so much gentlemen. very much appreciated.

i know ocduff, what could cause a relay to run hot but not blow? my first thought was that it was supposed to be a 25amp fuse, and that somebody had put in a 30 to avoid blowing, and thus the melting.

all of my electronics run strong (except maybe the wipers which struggle a bit at low speed) so i hope its not the ground-strap.

DDouglas, thats an interesting workaround. full-time fans. a good, solid, plan-B - thanks for the tip.

the_sicilian

Discussion Starter · #7 · Oct 1, 2007

my radio relay doesnt have a fuse.

while youre pulling out relays to get info for me, could you please also snap a shot of the other relays in your box? i have none for the lights-delay relay or the rear-defogger and i want to get those online (for the hardtop. it has an overhead lamp and defrosters)

thanks

ddouglas77

· #8 · Oct 1, 2007

the_sicilian said:
DDouglas, thats an interesting workaround. full-time fans. a good, solid, plan-B - thanks for the tip.

It is a cheap way, that is for sure. In winter I just unplug one radiator fan. Never had her overheat, just takes a little longer in winter for her to warm up. I got to get dressed and get that part # for you...

ddouglas77

· #9 · Oct 1, 2007

Part # BO47, mine has 30 amp fuse as well.

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ddouglas77

· #10 · Oct 1, 2007

ddouglas77 said:
Part # BO47, mine has 30 amp fuse as well.

Don't have time to get the exact part # for as B047 doesn't seem to exist anymore, this site: http://www.fujitsu.com/emea/services/components/relays/auto/
has it, I'm sure, I'll go through the old one and let you know...sorry, I'm hungry, got to eat.

msiert

· #11 · Oct 1, 2007 (Edited)

This is from a 1991 S-4 Spider. I seem to be missing a relay unless it's suppose to be that way?

The fuse that is pictured is the second one from the left on the drivers side............Love the diagram on it!

Which one of my relay's are the A/C relay for the pressure switch/compressor?

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4

ocduff

· #12 · Oct 1, 2007

I asked the same questions about the relay positions a few years ago. Since I don't have a scanner to copy my S4 Workshop book, here's the link the the thread about relays and fuses in the S4:

http://alfabb.com/bb/forums/showthread.php?t=10029

It may not help Guido, but it may just clarify for others.

ddouglas77

· #13 · Oct 1, 2007

msiert said:
Which one of my relay's are the A/C relay for the pressure switch/compressor?

I could actually read that wiring diagram! Guess my eye sight is improving or you got a detailed pic on that Murray! Top Right hand Relay is for your compressor. Pressure switch simply allows the current to travel or not travel, it is not fused per say.

msiert

· #14 · Oct 1, 2007

ocduff said:
I asked the same questions about the relay positions a few years ago. Since I don't have a scanner to copy my S4 Workshop book, here's the link the the thread about relays and fuses in the S4:

http://alfabb.com/bb/forums/showthread.php?t=10029

It may not help Guido, but it may just clarify for others.

Thank's ocduff, that wil be of great help!

ddouglas77 said:
I could actually read that wiring diagram! Guess my eye sight is improving or you got a detailed pic on that Murray! Top Right hand Relay is for your compressor. Pressure switch simply allows the current to travel or not travel, it is not fused per say.

Yep your right it is the far left hand fuse, I just got done checking it but it does have a fuse (10 amp).

Still your fuse box and mine are different I find that odd? I thought the 90 and 91-94 were pretty much the same except for body and interior?

ddouglas77

· #15 · Oct 1, 2007

msiert said:
Still your fuse box and mine are different I find that odd? I thought the 90 and 91-94 were pretty much the same except for body and interior?

No, the 90's had the drivetrain of the 91-94s, but not the power steering and the other odd ones with automatic transmissions. 1990 was the bastard child, 1989 waterpump, but twin electric cooling fans, V belt to the AC compressor, Motronic, crankshaft sensor at the pulley, not flywheel, etc...Heinz 57 if you will...

the_sicilian

Discussion Starter · #16 · Oct 1, 2007

the S4 doesnt have a V-belt to its compressor?? whoa. hows it work? i have two belts, do u mean S4 had just one belt?

murray, that is the same mfr and numbers as my fuse, but mine is grey with red under. maybe a revised part! tits! im going to order it. thanks for helping me figure that out

thanks so much for the photos guys. much appreicated. (DD yours was useless. may god have mercy on your soul

thanks for the fujitsu link tho)

the missing relay in your shot (second from right) is for rear-window defogger. radio is the one in the middle. the air-conditioner is the far-right and down with 30amp fuse. the white one.

here is S4 tech bulletin that outlines simply final fuse/relay layout i think:

kisses! --Guido Comparato

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ddouglas77

· #17 · Oct 2, 2007 (Edited)

the_sicilian said:
(DD yours was useless. may god have mercy on your soul thanks for the fujitsu link tho)

I was trying to show the 30 amp fuse, not the number. My part numbers are definetly different than Murrays, but the internal wiring is the same. I started a thread on here a while back ago on how to rebuild a relay, so if you wanted to save some cash, give it a search. Hold on, found it for you: http://www.alfabb.com/bb/forums/showthread.php?t=35231&highlight=how+rebuild+relay
Now, this Sicilian thing owing you a favor...Whats that all about? LOL J/K

CaverDave

· #18 · Oct 2, 2007

Something else you might check would be to test the current draw on the fan motor. A 25 amp fuse and a standard relay should be sufficient to run the fan with no problems. As the fan motors age and wear they slowly build up resistance and begin drawing more current. A very common problem on GM vehicles as DD should be able to verify, as the blower fans start aging they will build up current draw to the point of melting down the fan switch, relay, wiring connectors and fuse slot in the panel, but not actually blow the fuse.

ddouglas77

· #19 · Oct 2, 2007

CaverDave said:
Something else you might check would be to test the current draw on the fan motor. A 25 amp fuse and a standard relay should be sufficient to run the fan with no problems. As the fan motors age and wear they slowly build up resistance and begin drawing more current. A very common problem on GM vehicles as DD should be able to verify, as the blower fans start aging they will build up current draw to the point of melting down the fan switch, relay, wiring connectors and fuse slot in the panel, but not actually blow the fuse.

Very true, but most of the time *Not all of the time* the fans will begin making horrible noises-but you did bring up a good point, he should try rotating the fan blades by hand *key out of the ignition* and see if there is unusual drag in one or both of them. I would believe and papajam may know the answer to this, that any high draw of amperage will cause heat where it is being restricted. I would think *not saying 100%* that he has either very dirty contacts in the relay causing the resistance building up the heat or his relay coil has a short in it. Both would cause excessive heat at the relay, enough to melt a 30 amp fuse to it, but not necessarily blow it.

DavidH

· #20 · Oct 2, 2007 (Edited)

Hey Guido, Thanks for posting the tech bulletin drawings. Tell me, where did you find them? I have the Cardisk for the S4, which is supposed to have all the technical bulletins; but I dont recall that these were included. Do you have the number of the tech bulletin(s) that these were in? Thanks muchly. David

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