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Discussion Starter · #1 · (Edited)
Help!!! Brake lights, horn, cruise control DOA!! [SOLUTION]

[SOLUTION]
Well, I figured I would update this first post, so people wouldn't have to read all those responses...

I have an aftermarket look-alike spoiler. Whoever installed it did a piss-poor job on bolting it on and wiring it in. I had found an "iffy" splice-in a couple of months ago, so I tore it apart and re-tied it and re-wrapped it.

This morning, all my lights, horn, etc. started working again... except the spoiler.

I checked in the trunk, traced the wires back a little further into the conduit, and found where, when it was originally installed, they had apparently cut the wires too short. So, an additional cut was made and an extra 8" or so of wire was spliced in. All in all, there were three splices, I have fixed all three of them now, the spoiler lights up just fine now.

The questions still remain... Why didn't the fuse box do it's job and blow a fuse, if the wires for the spoiler LEDs were shorting out? Why was power going into the fuse box, but not coming out? Why was I not able to jump wire INTO the dead circuit?

Well, Mike Hughes has a fuse box on its way to me by Next Day Air, which I ordered yesterday, before it fixed itself. I will go ahead and replace it anyway. Hopefully, this one will blow a fuse when it's supposed to.

Thanks to all who offered advise and documentation!
[/SOLUTION]


Hello all,

I have searched and searched. I found several posts over the years from people saying that their brake lights have gone out, "REAR" light on dash comes on, horn does not work, and cruise control does not work.

Most of those posts do not have a solution listed. I have searched ProbeTalk, too, with the same results.

There is reference to a lamp relay in the trunk, but that only controls the tail lights. I verified that.

So, that leaves the fuse / relay stuff under the hood. I have checked there, but the labeling system on the fuse box cover leaves a little detail to be desired. There is:

MAIN
HEAD
IG KEY
DEFOG
BTN - What's this?
EGI INJ
ABS
COOLING FAN (4 of those)
HEATER
AIR COND (2 of those)
TNS RELAY - What's this?
HORN RELAY
DRL RELAY
ST CUT RELAY
EGI MAIN RELAY
CIRCUIT RELAY
and fuses:
TAIL 15A - which is fine
FOG 15A - which is also fine

I see there are other relays under the hood, but none of them seem to be mapped out anywhere.

I spent over an hour at the :flamer: dealership this morning and they are incompetent corporate pricks. The funny thing is how much more money they make than the guys at AutoZone, who will actually try to help. I just got shifted from person to person.

Anyway, they printed a parts list for me that also doesn't have any descriptions, only part numbers. Big help, fellas.

Can anyone please help? I have searched, I promise.

We have weather coming today and I am grounded until I get brake lights (and a horn wouldn't be bad either.)

Thanks!!!!!!!!!!!
James
 

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Check the "room" fuse in the kickpanel. There may be others blown as well but i would start there.
 

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Discussion Starter · #4 ·
Hey, thanks guys for the replies.

From what I can see, none of the fuses in the kick panel are blown. I checked the ones that looked like they could be related.

I will go back and check the "room" fuse. Isn't that the dome/map light circuit? Just assumed it wasn't related, I guess.
 

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mosheen said:
Hey, thanks guys for the replies.

From what I can see, none of the fuses in the kick panel are blown. I checked the ones that looked like they could be related.

I will go back and check the "room" fuse. Isn't that the dome/map light circuit? Just assumed it wasn't related, I guess.
i've had some wierd things happen when that fuse blew.. no audio.. no illumination on the dash (even though theres a separate cluster gauge) etc.

i blame it on electrical gremlins, but hey its a start.
 

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Discussion Starter · #6 ·
I'm just wondering if there isn't some water somewhere, or electrical that got wet... I checked the trunk and connections to the tails, no water. Moisture, yes. Always.

This past weekend I pulled the tails off and tinted them. Hooked it all back up, everything working fine. Now four days later the brake lights go out.

Anyway, just to be safe, I am going to go through and check every fuse in succession. I think I am going to ask for a multi-meter for Christmas. Does anyone here love me that much yet?

Santa?
 

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digital multimeters can be insanely cheap. for the most part, as long as you only need precision into the hundreths, one is as accurate as any other.. they only really become expensive, adn worth it when you need ultra precision calculated out the ten-thousandth and more.

dont get me wrong, if you need them, the expensive ones are certainly worth it. but i've not run into a situation yet, that my 5.00 dmm couldn't take care of. I also have a fluke dmm, and it was very costly.. but its not really suited to garage work.. its very quick, and has functions out the wazoo - and is great for logic board diagnostic (i bought it when i was in polytech, comp-engineering) but i would hate to get greasy hands on i lol.

here are a couple of multimeters :) i personalyl have the harbor frieght ones (when they were yellow) - i got 2 just to have on hand.

the sears one is more money but is also a bit better.. still not top of the lin,e but acceptable.

again, the cheapie one will do 99% of what you need it to in a car...

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=92020
http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=03482139000
 
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Discussion Starter · #8 ·
Thanks again, GC for all the useful info.

Here's an update, removed every fuse at lunch today (under the hood and kick panel) and not a one of them are blown. It's down to the relays, I guess.

There is a relay in the trunk, which, when I unplugged it, made the (currently working) tails and parking lights go out.

Do these things do multiple tasks, allowing the tail lights to work, but not the brake lights? I hate going through and replacing everything that is working fine just to rule them all out, in trying to get to the bottom of this. I can't afford that, but I'm afraid that's what this is going to come down to.

I'm sure a trip to the shop for some electrical work (quick fix) would end up being more expensive than replacing *everything* myself.
 

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Discussion Starter · #9 ·
Sorry about the two posts rule...

http://www.mx6.com/forums/showthread.php?t=102498 - A thread about screwing up some wiring and causing this to happen by blowing a 20A fuse, which runs the brake lights, horn, and cruise control. Fixed? Who knows.

http://www.mx6.com/forums/showthread.php?t=99251 - A thread about getting the car repainted and losing brake lights, horn, and cruise control. Fixed? Who knows.

http://www.mx6.com/forums/showthread.php?t=49092 - A thread about honking the horn (in celebration) until the brake lights, horn, and cruise control no longer worked... Fixed, by professionals. No details.

http://www.mx6.com/forums/showthread.php?t=69666 - Another thread about brake lights and horn (no mention of cruise control this time) ... Fixed by "brake relay" purchased from mhughes... From what I can see, also the fine folks at the dealership, there is no "brake relay."

http://www.mx6.com/forums/showthread.php?t=137341 - A thread about multiple problems, one being headlights & fogs not working. But someone suggested that he "check the brake fuse in the engine as well as the relay beside the fuse box" - WHAT brake fuse???????????

http://www.mx6.com/forums/showpost.php?p=1133232&postcount=10 - A thread about the pesky REAR light, where someone posted their experience with this. Said it was $114 relay that their mechanic changed for them, but don't know where it is from or what it does.

I have some e-mails out to some of these folks begging for more info.

I wish that people would go through and update their posts when problems are fixed. Otherwise, "USE THE SEARCH FUNCTION" doesn't do crap unless you just need confirmation that you aren't alone in having that particular problem.
 

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I definitely hear your frustrastion on that one - and wow, i didnt realize the problem was so esoteric and common! good luck - i am personally out of ideas, but when i get home i can dig up my factory service manual with its wiring diagrams.
 

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mosheen said:
Thanks, I really appreciate it.

I will, of course, keep working on it myself!
James
if you fix it.. i hope you will post results! lol lol
 

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Discussion Starter · #13 · (Edited)
I hope you know I will!

Since last night, I have been in front of the computer here at mx6.com and PT, looking through every flame war, brake fluid mishap, and LED brake light mod post there has ever been.

Right now I look like your avatar. I pulled all my hair out before wearing my arms down to bloody nubs!


[edit]
Now a full thirty hours since the problem came up... aside from six hours or so of sleep last night, this time has been spent searching these forums and the web in general for an answer. I have a 626 service manual (both LHD & RHD) that someone posted here as well as the 93-97 MX-6 parts list that are both absolute rubbish to this problem.

The 20A STOP fuse in the kick panel is fine. From what I gather, this fuse controls all the things that are not working. In case you skipped to the end and didn't read the title of the thread, that's the brake lights, horn, and cruise control.
[/hope]

:drinkup:

Good night.
 

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Discussion Starter · #14 ·
OK, here's the latest (and also a bump)

I talked to Mazda again... The lamp relay in the trunk is part number 67-660. The cost is $102.50 and they do not keep it in stock. They also can't tell me if it could go *partially* bad, causing brake lights to not work, while the rest of the rear lights work fine.

They did mention, however, that there is a model for W/SPOILER and one for W/O SPOILER. As mentioned in previous posts, my car did not originally have a spoiler, but a previous owner bought a look-alike MX6 spoiler and had it installed. When he asked if it was with or without spoiler, I thought... hmmmm.

So it would be a $100 shot in the dark. Since it is special order, there probably isn't a chance of getting one, running outside to plug it in, and returning it immediately if it didn't fix the problem.

Also, I swapped out the 20A STOP fuse in the kick panel for a new one, another shot in the dark, but no dice.

:damnmad:

I am not too handy with a wiring diagram, but if someone has access to one, I would greatly appreciate a hand with this. I'm wondering if a wire into the back of the fuse box, connecting the STOP circuit could be bad. I have played around with the wires back there, but don't see any problems.

I have heard mention of a ground possibly being bad in the trunk that could also cause the brake lights to go out. Also check the battery connections, which are clean and tight.

The brake on/off switch on the pedal is moving just fine, the connections are solid and clean.

So many things to check, no idea about any of them. And there is freezing rain out there right now. I am on a two hour delay for work this morning, because of the roads (you have got to love the southeast US)
 

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I guess the relay mentioned above can be a socal "check relay" wich monitor the rearligth bulbs, and ligth up the warning ligth if any of them goes.
I know some people have ruined this "check relay" with improper installed connectors for trailers or with trailers with messed up wiring.
I belive the symtoms you describe can fit a faulty "check relay"
 

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Discussion Starter · #16 ·
Following Goatcrapp's advice, I am going to go pick up a digital multimeter. I always assumed they were more expensive.

Does anyone know the procedure to check that relay with a dmm? What results are good / bad?

Thanks, FE3T! Karma to you too!
 

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Discussion Starter · #17 ·
mosheen said:
The lamp relay in the trunk is part number 67-660.
According to AutoZone, they can probably order a replacement for it, if Mazda had actually given me the first half of the part number. He was expecting 10-12 digits with multiple hyphens, I only got the last five.

I picked up a multimeter tester while I was there. $14.99, not so bad. A lot cheaper online, but I needed it today.

I found a walkthrough at an RX-7 site that suggested checking the wire harness going into the fuse box (there's a nasty little bit of interior trim there that I couldn't get off quickly enough. Would have required removing the door sills too) the wire harness going to the brake on off switch, and the switch itself with the multimeter.

As stated, I couldn't get the trim piece off to get to the wire harness for the fuse box, which ruled out checking the first two. I did, however, check the switch itself and it tested fine.

That's one down.

I went to the boot (I prefer that to trunk... ever since I started watching Top Gear, I may never be able to say trunk again) and removed the nasty check lamp relay. I tried to test the wire harness as well as the relay, but couldn't get a reading off of anything.

I really don't know what I'm doing with the multimeter just yet... Trying not to blow it up. Those tests really didn't tell me anything.

So.

:idea:

Do you think it would be possible to bypass the relay all together? If it truly is just a check relay, then, in theory, I could just jumper each of the incoming / outgoing wires in the harness... Driveway fire, anyone?
 

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I would take those extra trim pieces off and get behind the fusebox... not a problem in our cars so much, but i've seen plenty of other cars where a short melted some wires, with the fuse NOT popping.. in fact that happened to me when my upgraded fuel pump ran empty and burned out... really sucked.

you can get a replacement for that relay from mike hughes... it isnt so common a problem where you'd have too much of a risk of the replacement being bad also - i'm sure he would have them a lot less expensive than the dealer :) ask him for more than one maybe :) lol.

his screen name on this site is hughes46.

do you have a pinout for that relay? i'm assuming its not the same as a dpdt or dpdt relay, so the pinout would help with how to test it.... the tools would be the same however.. you can apply power where needed with a lead off of a 9v battery, for bench testing.
 

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Discussion Starter · #19 ·
Goatcrapp said:
I would take those extra trim pieces off and get behind the fusebox...
I will take that on when it isn't dark and sleeting on me!


Goatcrapp said:
you can get a replacement for that relay from mike hughes... it isnt so common a problem where you'd have too much of a risk of the replacement being bad also - i'm sure he would have them a lot less expensive than the dealer :) ask him for more than one maybe :) lol.
I have been contemplating doing that very thing. I wanted to figure out if that is actually the problem before spending any money on it. I'm a cheap bastard. Mostly poor, but a little cheap as well.

Goatcrapp said:
do you have a pinout for that relay? i'm assuming its not the same as a dpdt or dpdt relay, so the pinout would help with how to test it.... the tools would be the same however.. you can apply power where needed with a lead off of a 9v battery, for bench testing.
I wish I did. I can't find any reference at all to that relay around here. The parts list that is up on the FAQ is missing all of those. I have pinouts for plenty of other harnesses, but not that one.

I need to take a look around for some self-help on the multimeter.

"I stuck the red one up my butt and the black one to the driver's seat to measure my resistance..."
 
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