I have murdered my cars electrical system

[Sonic31]

I will not go into the details of the colossally stupid move I made yesterday, but let's just say the wiring harness got damaged as a direct cause of it.

The result of the damage was:
Car does start
Brake warning light lit on dash
Headlights don't work
Passenger bright works, drivers bright doesn't
Brake lights don't work
Door locks don't work
Indicators don't work
Wipers don't work
Windows do work
Don't know if the horn works (can find out)

So, yeah, pooched it pretty good.

I repaired the damaged wires in the harness today, but I have the same result.

I am thinking there must have been a short further up the line somewhere and I was wondering if anyone might have any idea what may have failed.

A few things to know:

I don't currently have access to the car (currently DOA in my friends garage)
I am likely going to have to tow it to a dealer to get it fixed. Mostly I am just hoping to educate myself about what the problem might be so I can speak intelligently with the dealership.

Any feedback, advice would be greatly appreciated.

Cheers

[Thrizzl3]

no move is stupid. just a mistake. it would give a heads up to others on who might have attempted to do what you did. Just share..i know i've made mistakes and posted about it lol...

[The Wolf]

Check all your fuses before you end it all

[Sonic31]

no move is stupid. just a mistake. it would give a heads up to others on who might have attempted to do what you did. Just share..i know i've made mistakes and posted about it lol...

Well the mistake was I got a tad impatient running some new wires through the grommet in the firewall and let's just say using a drill to try and save some time has turned out to be a fairly costly mistake.

[Sonic31]

Check all your fuses before you end it all

I have checked all the fuses on the panel inside the passenger footwell and they are all good. All the wires that were damaged were going to that panel so I think it might be something bigger than just a fuse.

To be fair I haven't checked any of the fuses in the engine bay yet.

[Thrizzl3]

Well the mistake was I got a tad impatient running some new wires through the grommet in the firewall and let's just say using a drill to try and save some time has turned out to be a fairly costly mistake.

hey man shit happens. But that's all about the learning process :) which harness was it?

[Sonic31]

hey man shit happens. But that's all about the learning process :) which harness was it?

Well it looks like two main looms come together at the grommet. But all the wires that were damaged are ones that run to the fuse panel in the passenger footwell. They all run to same main connector, the big green plug that goes into the panel.

[Thrizzl3]

Well it looks like two main looms come together at the grommet. But all the wires that were damaged are ones that run to the fuse panel in the passenger footwell. They all run to same main connector, the big green plug that goes into the panel.

eeek. that's serious...sucks that the wiring around the mazda 3 is one giant ball. Hopefully you won't have to replace everything

[Sonic31]

Yeah, I def hope so.

[McGuyver_3]

Damn it's to bad you are not closer to Toronto, I wouldn't mind taking a peek at it. I have a spare junction box from an 05 base model. Not sure what model and year you drive.

[Sonic31]

I would have been happy to have you take a gander :)

As for your spare, I drive an 06 5Spd ATX. So i don't think it would have worked. But I have started thinking that route and I have started looking around the local junk yards for a replacement unit.

Think there are some from my exact same model year avail for $120 which is a nice savings over a new one for sure.

Going to be spending a lot of time on the phone tomorrow I think :)

[Sonic31]

In a related question anyone have part numbers for a power junction box for the 06 models?

There is one from a hatchback avail in town here same model year engine and transmission, so I am thinking it should work in my sedan but it would be nice to get confirmation.

[McGuyver_3]

The junction boxes from 04 to 06 could be relatively easily swapped. 07 is when they started being different. In terms of AT or MT not sure. The junction boxes are known to be rather fragile although for the time I had my car I never really had issues. How badly were the wires damaged? Could it be that you have more then 1 wire with the Same colour? I have a electrical diagram book for the 05 which I would be more then happy to photocopy and send your way

[Sonic31]

When I had the loom apart (took it out from the grommet and electrical tape) I was pretty careful to check every wire for damage (three times). Turns out 6 of them had been either cut through or had the insulation stripped off.

I was equally careful to make sure I matched them back up properly when I spliced them together (i.e. orange on black to orange on black, and black on orange to black on orange).

I am pretty confident in my repairs actually. Soldered and shrink wrapped the 18 awg ones, and butt connected (the heat shrink type) the two 14 awg ones and the one 12 awg one.

I think when I started up the car after running some other wires, not knowing about the damage to the harness, I zapped the board. Kind of the only thing that would explain all those systems going down at one shot.

I'll call up the dealer tomorrow and get a part number so that I can compare it to the one from the junker.

If I plug the new one in and it solves the problem, the car should be able to function relatively normally enough until I can get it to the dealer to get it flashed for my key etc.. correct?

[ryan2.3]

is this the grommet behind the glovebox? When i was changing my cabin filter and unplugged everything from the fuse/cable tray, i thought i put everything in tight all the way. One of the connectors looked all the way in but wasn't and as a result, i didn't have any of my lights (interior or exterior), turn signals or locks. Maybe you fixed it but it's not in all the way?

[Sonic31]

is this the grommet behind the glovebox? When i was changing my cabin filter and unplugged everything from the fuse/cable tray, i thought i put everything in tight all the way. One of the connectors looked all the way in but wasn't and as a result, i didn't have any of my lights (interior or exterior), turn signals or locks. Maybe you fixed it but it's not in all the way?

Maybe, I'll double check when I am in there next.

[stock3]

Costly mistake indeed, but that's how things go sometimes even for professionals. The key thing is to recognize the mistake, fix it with a cool head and learn from it. That's what separates good mechanics/diy-ers from hacks.

I would not start hunting for parts until you are certain what's wrong. The junction box won't get fried that easily without blowing some fuses or relays. That's why they are there. Check everything twice, including the relays, which requires a multimeter, both in the engine bay an inside the cabin. Don't assume that just because the wires damaged were going to the cabin, the damage will be on that side.
Good luck and keep us posted.

[Sonic31]

How would I go about checking the relays with a multimeter?

I'm not the best when it comes to electronic testing so where would I put both ends of the probes? What setting should I have the meter on? What reading should I be looking for?

I'd love to sit down with a meter and check each wire, but I am not sure what information I'd be looking for or how exactly to interpret it.

I was mainly going to try and plug in the new PJB because it's kind of a carpet bombing approach to the problem.

[stock3]

How would I go about checking the relays with a multimeter?

I'm not the best when it comes to electronic testing so where would I put both ends of the probes? What setting should I have the meter on? What reading should I be looking for?

I'd love to sit down with a meter and check each wire, but I am not sure what information I'd be looking for or how exactly to interpret it.

I was mainly going to try and plug in the new PJB because it's kind of a carpet bombing approach to the problem.

No offence, but you're better off getting it done by someone else who knows what they are doing and understands electrical systems and knows how to diagnose them. You may end up shorting more stuff in the process.
It's good you want to learn, but situations like your are not exactly ideal for that.

Also, unless the new junction box includes all new relays and fuses, you are not "carpet bombing" anything. That's like changing the transmission just because the clutch went out.

[Sonic31]

No offence, but you're better off getting it done by someone else who knows what they are doing and understands electrical systems and knows how to diagnose them. You may end up shorting more stuff in the process.
It's good you want to learn, but situations like your are not exactly ideal for that.

No kidding :)

Agreed.

Never mind the fact that at the moment my car is holding my friends garage hostage, so time is of the essence here as well.

I am thinking that if plugging in a new PJB doesn't do the trick then it's time for a tow and I'm going to have to cross my fingers this doesn't end up costing me too many organs to get fixed.

[lcianf01]

i agree with a past post. Ensure that all the connections are firmly seating in the junction box.

when i changed my cabin filter i put everything together the door locks and i believe the horn didn't work. after freaking for a little i rechecked all the connections and found one that was not seated correctly and problem was solved.

Hope it works out for you.

[McGuyver_3]

The relays are part of the circuit board on the North American models, the only relays I know that are demo eagle are the ones under the hood. I would lend him mine but we are not exactly 5 minutes apart. Mine is a known good one as it is missing auto light and wiper feature. Reason I swapped it out of my 05 as I did that upgrade. As for keys reprogramming is easy, it's a sequence with unlock and lock doors and turning off and on the ignition. Can't remember the exact procedure but something along those lines



How would I go about checking the relays with a multimeter?

I'm not the best when it comes to electronic testing so where would I put both ends of the probes? What setting should I have the meter on? What reading should I be looking for?

I'd love to sit down with a meter and check each wire, but I am not sure what information I'd be looking for or how exactly to interpret it.

I was mainly going to try and plug in the new PJB because it's kind of a carpet bombing approach to the problem.

[Sonic31]

Thought I would post up a somewhat delayed update.

So first things first I had to get a tow to the local dealer. So rather than pay for a tow truck I ended up buying CAA and just used them to tow it. Saved me about $50.

Once it got to the dealer they ran the standard tests. Alternator is OK, battery is OK, but low and behold they found 2 blown fuses.

One was for the left high beam and the other was a 40amp jobbie (part number EG51-67-099) that I guess runs just about everything lights related.

Total cost in parts $4.13, alt/battery test $70, labour for diagnostics and fuse replacement $117. So $220 after tax.

Pretty expensive for replacing a couple of fuses but worth it to me because it wasn't $1000 for a new junction box. Also I probably never would have figured out where the problem was and I was beginning to wear out my welcome in my friends garage :).

All in all it was a pretty good learning experience and I'm pretty happy with the outcome.

[Thrizzl3]

Good to hear man :)