Help with REAR DEFROST

[duaux]

1st off just wanted to say that my 2nd hand RED '94 MX-3 5spd is my first car, and im enjoying it so far!

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However here is my small problem.

REAR DEFROSTER does not turn on, the light or the defroster does not come on. After i came out from the gym... it just didnt turn back on. (2hrs away) weird. it was working fine before then.

My rear wipers do work however just incase some may be wondering... ive read that some ppl with the same problem did not have their wipers work as well. my wipers do work.

Areas that i have checked:
Fuse's, they seem fine. Ive even bought a new one and changed the rear defrost fuse.

Areas that look suppicious:
Relay and Wiring Harness

The relay does make a "click" noise when press the defrost buttom. So i think it is the right one. The relay has this info on it.

H270 (big letters)
DC12V20A
IMASEN
2G18

But the wiring harness... looks kinda "rusty"?

My question now is,

1. Should i buy a new wiring harness and relay and change them myself? since this is a cheap solution. if so how do i change them?
2. It is another problem in which someone can eloborate on...

Any comments appreciated ASAP since its now getting cold in Toronto...

[Grants]

If the relay is clicking there must be power somewhere so it won't be the fuse. Does the little light come on in the switch?

The weakest point of the demister is usually where the wire connects to the glass. Have you had a good look at that connection?

[duaux]

hey grants,

thx for the reply.

the light does not come on in the button.

how do i test the wire that connects to the rear defroster?

[Grants]

If the light doesn't come on its unlikely to be the connection at the window. So. Looking at a diagram, does your hazard lights work? (They share a ground with the defogger switch.)

There are also 2 fuses that need to be ok, the "defog" fuse (in the engine bay?) and fuse number 9 under the dash, which is the "meter" fuse. Can you check this one too - or better still change it anyway in case its blown but still looks alright.

[MarkMoore]

ok, i just wanna put my 2 cents in here, even though it'll probably be worthless to you... unless by some unlikely chance you DO have the same problem that i have... in which case my 2 cents will indeed be worth a lot more than 2 cents... ha uh yeaaaaaaa... anyway i bought my mx-3 in june and the rear defrost never worked... however when i hit the defrost button, the button itself DID light up... this confused me... upon further review... we found that the defrosting strips had been damaged when the previous owner put on an EXTREMELY EXTREMELY light tint (i personally refuse to believe that it is tinted, but that's what i'm told) on the hatch... apparently this happens sometimes when rear windows are tinted... the tinting person somehow in the process damages the continuous defrosting strip thereby ending any kind of defrosting capabilities... doesn't seem like a good trade-off does it? gaining an unnoticeable tint for rear defrosting... but cheer up guys, don't worry about me, my parts car to the rescue!!!! the hatch color is different, but at least the defroster on my parts car works, and soon it will be painted and on the driveable mx......

<small>[ November 09, 2004, 12:05 AM: Message edited by: MarkMoore ]</small>

[duaux]

hey thanks for the replies guys,

Mark: i have no tint on my car, but it was nice to know that a tint my harm the rear defroster. will take that into future considerations when tinting.

Grants: i did changed the DEFROST fuse in the engine compartment, but i did not change the METER fuse since it "looked" perfectly fine. My hazard lights seem to be working as well.

Anymore ideas guys?

thanks

[Grants]

Just swap that meter fuse with another one just to make sure but if the relay is clicking it shouldn't be that. Best to make sure though.

Can you check voltages? At the defog relay there should be a BLUE wire which should be 12 V with the ignition on. When you press the defog switch, the relay should click and the BLACK - BLUE wire should liven up to 12 V.
If you have voltage at the BLUE and the relay clicks but you get no voltage at the BLACK - BLUE, the relay is u/s.

Can you find another relay the same (headlights, air con, etc) and swap it over for a test? That will prove pretty quickly if the relay is the fault.

Good luck!

[mx3optidrive]

I answered this before in another section I think. My relay was still clicking and I changed it anyway and it worked ever since. My relay was faulty and when I unplugged it from the harness, I noticed that the harness itself was burnt and some of the wires were too so I had to change the harness as well. Chances are it is the relay, it is only like $3 to replace.

Jeff

[duaux]

hey guys thx for all the replies so far.

i think i will do the following in order when i get some time between school and work

1. change the meter fuse eventhough it looks ok
2. buy a new relay and wireharness and change it since its not expensive... 10-15bux total?

question now is, how do i do the swop?
do i just cut the old one off and and wire the new one on?

[Grants]

The wires just plug into the bottom of the relay so you can just unplug it and plug in another one.

Before buying a new relay you should prove the existing one is no good. There are numerous relays the same scattered about the car. (If you have air conditioning there are some under the hood near the firewall that are easy to get to.) Simply pull one out, unplug the defog relay and plug in the test relay. You could spray a bit of WD40 or something into the plug before plugging the test relay in too. Only take a couple of minutes.

[mx3optidrive]

Just to let you know what caused my relay to short out, it was from the salt they use on the roads around here that got into the plug and shorted the relay out and burnt out the relay prematurely. The guys at Mazda said if I didn't catch it, it might have caused a fire. By the way the plug looked and the wires, I think they were right. Like I said earlier, the relay was clicking and I thought it was working fine until I changed it.

If your wires and/or plug are not burnt or damaged, all you have to do is unplug the old relay and plug in the new one. If it is damaged, you have to make up new ends for the wires and plug them into the right poles on the relay.

Good luck man. I hate the Canadian winter and that is why I store my car now. Let me know if this helps.

Jeff

[duaux]

damn. actually my wire is kinda damanged...

the connection on the wire harness, the two "thicker" wires i can c the metal...

all the other relay and wire harness connections look fine.

but tomorrow is my day off so i hopefully i can figure this problem out!

ill keep you guys updated.

[duaux]

well i still havent fixed my problem yet, but i guess i should atleast update my status for those who may have searched and found this post based on a related problem.

i was able to isolate my problem down to wires on my relay being faulty...

ie. the connection is kinda loose since it looks like it is deteriorating...

when i hold it together, i was able to turn on my rear defroster. so i think the solution to my problem is to just solder the wires back on carefully.

since its friggin cold right now, i dont think i will be doing... ive been driving awhile without it and so far no major problems

ps. i did some research since i almost completely gave up on the problem to fix it myself and found that the relay at the mazda dealer cost $29bux, and service at mazda dealers is $85/hr. all prices are in Canadian Dollars, Greater Toronto Area.

[Grants]

At least you found where the fault is! You sure they need soldering? I would have thought those terminals were crimped. Anyway, whatever works and hope you get it fixed ok.

[FiReSTaRT]

How do you recognize which relay's for the defogger if it's not clicking? (95 RS)

Do I have to get it at the stealership or can I get it at the canadian tire or parts source for less $$$?