[picassodavinci]

I know I'm reviving an old thread, but I thought I would add my experience, and hopefully help someone else with a similar PJB issue. Picked up an '04 Mazda 3 hatchback, and noticed after the sale that the tail lights, license plate lights, and interior illumination weren't working. Did some research, and with the help of this forum, narrowed it down to the TNS relay inside the PJB. Without access to the backside of the circuit board to unsolder the relay, I came up with a relatively easy workaround.
I didn't want to buy a used PJB module, or attempt to separate the two circuit boards. Instead, I carefully removed the old relay using a dremel and thin cutoff wheel, leaving a portion of the copper legs soldered to the board.
I bought 5 relays on Ebay, and waited the week for the slow boat from China:
5Pcs CQ1-12V Power Relay Automative Relay 20A 12VDC 5 Pins | eBay
I removed all the plastic bits to allow for a good solder joint and then soldered the new relay in place on the outside of the board. The new relay sits about 1/8" off the board, which is fine.

Total cost = < $20 (and I have 4 spare relays in case another one goes bad)
Hope this helps someone out there.

 

[picassodavinci]

This is the TNS relay:

 

[picassodavinci]

TNS relay removed - showing the five copper leg stubs left in:

 

[picassodavinci]

And the new relay in place:

 

[picassodavinci]

that's a good idea - I didn't debug the relay, I basically just took a chance, figuring electrical failures are typically actually mechanical failures (relay contacts).