[DCM6]

Here is my first how-to, so here it goes.

I was having problems where my back-up (reverse) lights were not turning on on my 2004 M6S (6-cylinder) with manual transmission was shifted into reverse. While I am still having problems with this, I took pictures and got details on how to access and remove the switch.

Here are the tools you will need:

* 14mm combination wrench
* 21mm combination wrench
* #2 Phillips Screwdriver
* Continuity tester
* At least 2 differently-colored test leads with alligator clips

Steps:

1. Open hood
2. Unclip 2-wire harness connected to driver-side of the airbox next to the fender.
3. Unclip the MAF sensor on the top of the intake tube (just forward of the battery)
4. Remove the accordion intake tube from the airbox by first loosening the clamp with the screwdriver, then gently removing the accordion from the tube.
5. Remove the air filter and airbox by firmly but carefully pulling up on the airbox. No screws hold it down, but pegs on the bottom of the airbox push through some rubber bushings which hold it in normally. This exposes the top of the transmission
6. Looking back towards the back and slightly to the passenger side, locate the backup switch. It is under the battery and just fore of the starter and the starter bracket as shown below:

7. The switch itself will take a 21mm combination wrench to remove, but you should remove the 14mm bolt just to the left of the switch just to make it easier. I noticed a bad smell after removing the bolt, (no, it wasn't me) and thought that it was probably from the loosened bolt.

8. Before removing the switch, go ahead and unclip the socket from the switch itself:

9. Unless you have a short 21mm socket that will fit, I found the combination wrench (the box side) worked well.

10. Keep the wrench handy as it takes quite a few spins to get it completely off of the transmission and my fingers weren't strong enough to unscrew it by hand only.

11. Inspect the switch itself. The travel of the plunger is only about a 1/4 of an inch. It should spring back automatically when pushed.

12. Also inspect the top of the switch to inspect for breakage or bent pins:

13. Test for continuity when the switch is pushed in by using the test leads (if necessary). If you get continuity, the switch is probably working. Screw the switch back in (finger tighten) and test for continuity when you shift into reverse. You should get continuity when shifted into reverse.

14. Test for resistance. If there is any resistance (anything more than 0 ohms), you may still have a faulty switch. If this is the case, you may have to replace the switch even if you read continuity when the switch is actuated.

15. Since the switch is connected by at least two small harnesses to the main harness, you could try jumping the pins on the side that goes into the car's wiring harness (and have someone step on the brake + clutch, turn the car on and shift into reverse) to see if the lights turn on. If it does, perhaps the problem is in one of the short harnesses mounted to the transmission.

16. Reassembly is as simple as following same steps from step 10 back to 1.

Good luck!

 

[kpjimmy]

Nicely done! Methinks this is sticky worthy. Thanks for the write up!

 

[quakerjoe]

Great write up. I just replaced my switch and it only took about 15 minutes start to finish. I had to special order the switch though and that took a week and a half to receive it. BTW the part number is AC05-17-640A for those who can't find or get ahold of it any where else.

 

[Mazda6dude]

Did you ever figure out why you are having this problem? I am in a sticker state and I won't be able to get a sticker if my lights do not work. My car has been trying my patience. All sorts of major and minor problems. I haven't figured out what this one is yet.

Addendum: This is a great write up however a SAE 13/16" wrench fit better on the switch. It sure as hell didn't want to come out of there. I ended up having to remove the bracket above and towards the passenger side also to get a better angle at it. In the end the back up lights worked! Ka ching!

 

[Steve O]

Hey Guys,
i just realized that I am having the same issue. thought it was just the bulbs but ruled that out.

Can you tell me if this fix is the same for a 2005 model?
Thanks,
Steve

 

[TalonTsi90]

I believe an O2 sensor socket will fit.

 

[anupk]

Hi,

What is the Back Up Light switch part number for 2003 Mazda 6, 3.0L v6, petrol model?

 

[familyman333]

Any idea what to do when the notches on the switch are stripped? I finally found a 21mm combo wrench only to find that the switch won't budge cause it is stripped. Now what?

 

[Byakuya]

Resurrecting an old thread here but I just started having this problem on my 1st gen V6.

1. I just spent the last couple hours checking everything I can think of. It's not the switch, it's not the fuse, I checked the continuity of them both.

2. I checked all the wires with an ohmmeter and I've narrowed it down but don't have a wiring diagram so I don't know what else to test.

3. The continuity of the ground is working perfect the whole way, from the bulb to the switch. The power is working from the switch to the fuse box at the driver's seat, but not the rest of the way. I've checked all the fuses in that box and they're all perfect.

Does anybody have a wiring diagram or know if there's another relay or fuse that I need to check?

Thanks for any help!

 

[ZoomDog]

Any idea what to do when the notches on the switch are stripped? I finally found a 21mm combo wrench only to find that the switch won't budge cause it is stripped. Now what?

Yeah, I've got the same issue. Any ideas on how to get this damned switch out so I can replace it or should I take it to my mechanic and let him have a go at it. Any advise would be most appreciated.

Thanks in advance.

 

[ZoomDog]

Bump

Yeah, I've got the same issue. Any ideas on how to get this damned switch out so I can replace it or should I take it to my mechanic and let him have a go at it. Any advise would be most appreciated.

- any help or advise would be great.

 

[Kassa42]

Images?

I am dealing with the same issue right now and this is the most useful post I've found about it. Unfortunately the image links are all broken - does anyone know where a copy of this post might exist with the images intact?

 

[Final Impact]

FWIW: To eliminate the switch as the source of evil, once unplugged insert a pair tweezers into the open harness connector to short the pins to each other. BE VERY CAREFUL AND INSULATE THE TWEEZERS or paper clip or what ever you use so it doesn't short to a ground surface - Now go check the back up lights. If the switch is bad, they should be lit with the pins are shorted.

Google "mazdaserviceinfo" and good things happen with those part numbers.
9999-95-063B-06 Work Shop Manual
9999-95-039G-06 Wiring diagram
9999-95-078C-06R Owners Manual (USA)

 

[EntilZha]

Hi,

Last week I had to deal with this problem in my 6. This was the only useful publication that I found on the Internet, the only problem were the broken image links, so I decided to take some photos myself.

Sorry about the quality, they were taken with my phone.

Also, my 6 is diesel so don't be surprised if you see something different than yours.

Hope this helps!


Overal pictures:








After removing the battery, the intake filter and a tube (the reverse switch is under the tube in the picture):




The new reverse switch:

 

[mdhusker]

Just finished this last weekend and figured I would offer some real world experience. Since I was planning to replace the switch, this method should work for most. I removed the two 10mm bolts holding the metal bracket to the transmission case that has the second plug to the reverse switch and ground attached to it.

When I was trying to get my 21 mm wrench over the blue plastic top of the sensor, it started to strip the bolt - it was too tight. I was ready to remove the starter to have a better angle on the sensor plug, when I noticed the 13/16" spark plug socket(in most socket sets) was just small enough to fit under the starter, my large 21mm deep socket was about 1/2' too long.

I was able to use the 13/16" spark plug socket with two long extensions on my socket, then using my 2 1/2 ton floor jack handle as a breaker bar - I broke loose the sensor - it was torqued well at the factory or had 100,000 miles to set??

 

[willygoat]

Does anybody have a wiring diagram or know if there's another relay or fuse that I need to check?

Thanks for any help!

I'm just new and jumping in with the same issue on my 2004 6S

As far as wiring diagrams go, the owners manual actually has a bunch of wiring diagrams in the back. I was looking through them the other day. Might be work a check.

Thanks BTW for this nice walkthrough. I'm going out the garage right now to check my reverse switch.

Willygoat

 

[kidshelleen]

I believe an O2 sensor socket will fit.

I just took mine out and used a 21mm crowfoot wrench (new crowfoot set - yay! more tools...). My 21mm 12-point combo slipped/rounded. I didn't have a 13/16" 12-point to try. The 13/16" crowfoot (...again, more tools...) was too small.

I did bruise a thumb when it broke (3/8" ratchet handle with 12" black pipe slip-over extension).

So it sounds like a fairly honest 21mm. The crowfoot was perfect.

 

[KenOverton]

Need some help that is not covered above. Reverse lights are out, grounds are good, I am getting 12v at the bulbs but they won't carry a load. (swapped bulbs for LED's and they work). I jumped the pins at the switch and get the same results, so the reverse light switch is not the problem. I have a wiring diagram that shows a reverse light relay, but the 2 manuals I have do not give the location, and it is not located in the junction box under the hood or in the driver's side fuse box. Does anyone know where the relay is located?

Ken

 

[caldep]

I hope you find what you need. Just had to change the backup light switch. Nothing worked to get it out, crows foot, 13/16" socket, couldn't get the 21mm socket on it. Tried 21mm wrench but it just slipped. Thought I was going to have to remove the starter.
But I was able to get it out with a 13/16" combination wrench. The twelve point end.
To get the wrench on the switch I drove the box end onto the switch using a hammer and long pin. It did the trick.
But took about ten minutes to work the wrench back off the switch once I broke it loose.

 

[caldep]

Ken, I'm in the same boat. My new switch did not solve the problem. Normally I am very strict about not replacing parts until I've confirmed they are the culprit. I wish I had this time. Now to begin troubleshooting.

Unlike you, I have no voltage at the lamps.