Found homeless wire, need to find it a home.

[PappaRayman]

ENGINE/DRIVABILITY - crank no start

Year/Make/Model: 2007 Mazda 6 MPS
Mileage: 187000 kms
Location: Cape Town - South Africa
Concern: found homeless wire after rebuid
DTC's: none after scan
Modifications: CAT fooler insalled by previous owner
ECU/Tuning Software: none
Tuner: NA
Is the concern intermittent? No
Can you duplicate the concern?
Recent Repairs: engine rebuild after timing tensioner failed
Correction:

History on car: car ran perfect, had timing chain jump, bent vales - you know the rest....
Mechanic repairs engine, but notes dodgey electrical work done by previous owners mechanic. His auto electrician repaired where he can, and eventually pulled out saying to replace full harness.
Put car on flatbed and brought home.
I've been working on her in spare time.
I replied the harness points and tested continuity on all points. Repaired starter solenoid that failed, installed and now the car cranks, but no start.

I found a loose homeless wire that I can't find where it should go to or terminate to. I think there is a part/connector missing, but don't know..

Pic1 from friends harness, blue is for water temp sensor, green is what I should have.

Pic2 my harness after I found cable and it shorted and green insulation melter off, no connector and homeless. Blue is running to water temp sensor.

Pic 3 is a screenshot from friend (from video) of water temp sensor plugged in, and where on his car, the homeless cable should terminate to. Lol black box thingy.

I have no idea what it terminate to,what the part is, or what role it does. Hopefully you all can help?

Side note - I also found on front gear box only 1 of 2 grounds (left one " missing") not sure if this would also cause a crank no start. Rest of grounds what I could find are in place.

 

[dinnerplate]

It's a capacitor for the radio system for gen 1 speeds (3 and 6). If you want the P/N, I can go pull it off my car, but it harms nothing other than audio quality (if you actually use the AM/FM radio, that is).

With a crank no start, check the ground on the coil harness itself. If there's no ground there, the coils aren't going to send and current for the plugs to spark.

This tab right here (sitting on top of the cam sensor):



Normally, that's grounded to the plate that the connectors all mount to, which has bolts going into the lower HPFP housing that holds the follower and cam.

Additionally, you may just have no MAF connection being made. You can check this by modulating throttle while turning the key. It'll turn over with no MAF connection, with a little help from throttle.

Do your basic checks. Check for air, compression, spark, etc. And yes, those grounds matter.

 

[PappaRayman]

Thanks, I'll double check that ground spot. Maybe it's dirty or another dodge joint.

And thanks for the info on the radio capacitor, odd place to put in in an engine bay of you ask me. Radio and CD player work fine, so I'll just tape it up and make sure it doesn't short again.

I'll report back with (hopefully good) news.

 

[PappaRayman]

Ok, so coming back after a few days of checking, hunting and testing....

The green colored wire, I put some heat shrink on to re insulate it as it was bare, and put that aside, then spent some time and there's definitely no spark. Checked the fuses and relays, and they are fine.

Not sure why I would get spark as the lil ground wire that connects to the cylinder head cover (tappet cover as we call it here in SA) is on and I ran a extra wire to the negative terminal for Incase and still nothing. Going to spend some time on Google and see if I can find a idea to work from, bar that - tow her in to another shop and let them figure it out.

 

[dinnerplate]

What about the passenger motor mount ground? Is that connected? Those can cause problems, especially since the threads of the bolt are what ground the engine to the chassis. So take a look at that and make sure that ground point is clean.

 

[PappaRayman]

Hi all

So to come back to my post. I managed to ship in a new harness from Amsterdam with all the bits needed.
installed and guess what - no start, lol ! eventually got some cash and took it in, had the wiring checked and came down to damaged ECU. had it "repaired" but the local ECU specialist was complete tool so got the unit back and didn't end up paying for the "work" done. Great for going though a decent workshop... but luckily they fought the battle with the ECU guys for me. Fast forward two weeks, managed to track down a used ECU, now to get it programmed... will keep you posted.