Electrical issue: power locks, interior lights, turn signal

I’ve been having a handful of small issues with my Speed6. The latest issues are electrical.

Simultaneously, the power locks stopped working, the interior lights don’t come on when opening doors (but the overhead lights work switching them on manually), and the turn signals stopped clicking/flashing although they do come on.

I’m assuming they’re all connected somehow. Any advice would be appreciated.

 

Bad ground? Check <here>, from my post where I had issues with my signals and some other circuits.

 

Thanks I’ll check it out! I actually tried to improve that connection a year or more ago. Perhaps my work failed so it’s definitely worth investigating. Would be awesome if that’s all it is.

 

Ok, I redid the ground as best as I could and it didn’t help.

This may or may not be significant, but I wasn’t able to get to the inside of the white plastic piece. I’m assuming you pull the metal pieces out the front, I just wasn’t able to get it easily and was concerned I might break a metal piece trying.

 

PDL, interior lights and signals could be connected through security system, and/or BCM. Perhaps try checking wiring to related components. Is the issue intermittent at all or constant?
Any codes for CANBUS hiding in memory? Commonly wont activate CEL.

 

Yeah I need to investigate more. I should check every fuse and relay and also the wiring as you say, though figuring out wiring is my weakest point!

All I have for reading codes is my Accessport and ODB Fusion for my phone.

I did come across someone with the exact same issue and the recommendation was to replace the BCM. Even if I get a cheaper used BCM I suspect it’s expensive to get the dealer to program it. I hope it doesn’t come to that.

 

Also, it’s not intermittent. All of the issues showed up suddenly and haven’t gone away.

 

Might be worth having a dealer hook up and see what they find. But that has a small cost.
If you have time, wiring diag. is your friend. Get down and comfortable with checking for voltage, ground continuity. Look for anomalies. Also meter for broken wires. Try disconnecting lock solenoids, light bezels etc. If systems return, you have isolated the area of a possible short etc.

 

One weird thing is that if I activate the turn signal the dash light for the other side sometimes also lights up, and when that happens usually it is dimmer than the correct side.

 

That is a classic bad ground manifestation. That was what my car was doing, unfortunately for you, the white ground block didnt fix it. There are other ground points along the harness that could be suspect. But it could be a module issue too.
Do your hazard lights work? If that system works and your signal bulbs are situation normal, some your signal circuits are probably safe.
Do you have advance key? working? Or do you only have standard PDL? Is your PDL remote working or is it a complete black out?

 

The hazards come on but don’t blink. Like the turn signals.

I know of the one white plastic ground, the HPFP ground, and the one over by the power steering pump. Where are the others? Is there one near the starter? If so, I replaced the starter a couple of months ago and maybe I didn’t tighten something properly.

This link below is the key I have. It doesn’t lock/unlock the car, but I don’t know if it doesn’t activate the alarm at all or if it does but just doesn’t lock the car.

https://northcoastkeyless.com/wp-content/uploads/2019/04/MAZRHK5R-MAIN1-768x865.jpg

 

There is a ground from the battery that goes down to the starter bracket. However I would think the starter would have issues due to its high draw.

Check the fuse "BTN" in the engine bay panel, its a 40A. Also, while the fuse is out, meter for 12V.
Check the fuse "ROOM" in the passenger compartment panel, its a 15A. meter for 12V.
You can also meter the blue/red wire that goes to your ODBII port. It should have 12V.
Do your map lights or trunk light work?

 

Thanks for the suggestions! I’ll do those later today.

I remembered I had paid for the extended Mazda diagnostics with ODB Fusion. I’m not entirely sure how to use the extended diagnostics, but I noticed it has the BCM and various other things. I did find codes U0100 and U0121 in there somewhere (not the normal code scan and no CEL). I don’t know if they’re recent or old.

I’ll post back once I’ve done what you’ve suggested.

 

Those codes are most likely old, PCM canbus and ABS canbus anomalies. They dont mean much without other codes to back them up.

 

It was raining so I didn’t get to do any work on the car. Hopefully it’ll be good weather tomorrow.

 

Well I ended up getting the battery tested and it was good, and today I just replaced the alternator and belt tensioner (both used). My electric issues are fixed.

However, I had also been having an ABS issue so I disconnected the wheel speed sensor so that it’d stop coming on. So I’m not sure if it was the alternator or a short in the ABS system… I’ll get around to reconnecting the sensor at some point.

 

Good to hear