My electical system is going crazy..possible multiplex unit problems

[MightyMouse]

Well, my 05 Mazda3 GT Sport is starting to go crazy and I think I have a problem with the mulitplex unit. Anybody else have similar problems....here are just a FEW of the issues...

-keyless entry only works once in a while
-dome lights will come on randomly while driving
-gauges do reset-sweep when car started and trip computer resets to 0.0
-radio/clock reset when car shut off and sometimes radio/clock will not work at all, sometimes radio flashes "Hello!" while driving as if car just started

Damn mulitplex unit (inside fusebox under glovebox) is really expensive, too bad the warranty has already expired.

Anybody else have similar problems?

 

[TheMAN]

did you make sure all the connectors are seated fully in the PJB? it could cause weird problems like these

and the PJB is not user replacable... you have to have the dealer do it as it comes "blank" and has to be programmed

 

[MightyMouse]

did you make sure all the connectors are seated fully in the PJB? it could cause weird problems like these

and the PJB is not user replacable... you have to have the dealer do it as it comes "blank" and has to be programmed

Ya, I pulled it out and re-installed it, making sure all the connectors were good.

FARK!

Nothing I hate more than paying some other tech to work on my car.....

 

[tsunami]

i had some similiar issues especially the re-start while driving and my negative battery connection was flaky, new hardware and a tightening everything down made it go away... but i never had any thing like the lights going on/off randomly so its probably not it but tossin it out there anyways.

 

[TheMAN]

Ya, I pulled it out and re-installed it, making sure all the connectors were good.

FARK!

Nothing I hate more than paying some other tech to work on my car.....

if any of the connector "blocks" are partially above the white plastic rim of the PJB's connectors, it's NOT seated all the way.... the connectors must be flush all the way against the white rim of the PJB connector... it's very easy to not have it connected properly due to the retention style of these connectors

if you are sure that the PJB is ****** up, then do bring it to the dealer to get it replaced... they'll probably want to diagnose it, but just make them change it if you are sure its the PJB... note once you change the PJB, it will be an updated part, so the fuse locations will be different... you will need to refer to a 06 or newer manual for info or replace the plastic under cover with the 06-08 one

I replaced a PJB before because this car that came in had a weird problem where it had parasitic draw... the battery will die out after a couple of days... after running a few hours of tests (including testing the trunk light switch per a bulletin), it was the PJB... replacing it required the data to be backed up into the mazda diagnostic scan tool, then installing the new one, then flashing the data onto the new one... not something you can do in your own garage

 

[MightyMouse]

Thanks for the tips. Luckily, the tech that used to work in the bay beside me has gone to a Mazda dealer, so he can help me out to program the new one if I change it.