Short story
Doors will unlock, but they won’t lock. The Taiko TB2-100P relay on the body ECU (printed circuit board inside the Driver Side Junction Block) most likely failed. I bought a new Driver Side Junction Block that has a Panasonic relay on the ECU instead of the Taiko. I replaced the junction block (it’s plug and play), and now the doors lock and unlock properly. Completed the repair in a lazy hour and 20 minutes.
Long story
My doors quit locking when pressing the lock button on the remote key fob and when pressing the lock switches on the driver and passenger doors. They would unlock, no problem, but locking was right out. Several threads are available on this subject, but this one seems to point out why:
Body ECU test bad, or does it?
Specifically, the Taiko TB2-100P relay on the printed circuit board (aka body ECU) inside the drivers side junction block, has been found to fail in body ECUs across Toyota models. The replacement junction blocks are said to contain a Panasonic relay on the body ECU, and indeed I can confirm that my brand new, 2017 (or so) replacement junction block has a:
Panasonic
50810K1 1015 JAPAN
ACTB31N02
relay in the location where my old junction block has a:
TAIKO
TB2-100P
12VDC
0152 20
The Durk wisely and frequently points out that we should do diagnostics on the electrical parts before just buying stuff and plugging it in. He’s right. I thought I’d actually do the diagnostics, but for reasons I don’t want to admit (ok, I’m lazy, stupid, and impatient... there), I didn’t. Rather, I relied on
believing real hard that the problem was with the Taiko relay. Maybe I’m finding faith. Maybe not. I tried
believing real hard that the doors would just start locking again after whacking the junction block, sticking tennis balls in there, etc., but here we are.
So, my inner cheap bastard had me in a headlock for awhile on purchasing the junction block. My options were:
- Continue locking all 5 doors manually: This is supposed to be a fancy old truck. Manual door locking ain’t all that fancy.
- Get a salvage junction box: It’s a crap shoot. Might find one, might not. Might work, might not. Might work, but not for long. Might have to do it all over again all too soon.
- Try to find the Panasonic relay and replace the Taiko relay on the existing printed circuit board: Downtime while truck’s disabled, unknown time spent trying to find the part and get someone to do the repair (or gear up and learn soldering), unknown cost and time to complete. Might work, might not.
- Buy an OEM replacement junction box and change it myself: I own the risk if the new part doesn’t do the trick. Might work, might not. I could blow $473 and still have to lock doors manually. Then there’s the slicing of the fingers and the smashing of the knuckles...
- Take it to the Toyota dealer: Electrical parts damage risk is theirs, not mine. If they don’t fix, I don’t pay. They’ll probably find a way to do it wrong and mess up other stuff while they’re at it. They’ll charge an astonishing amount of money and it will take my beer fund a long time to recover. I’ll have to try to do QA on them before I take delivery. They’re unpleasant. I don’t like them.
My inner cheap bastard and I agreed on buying and doing the work myself. A grudge lingers.
I confirmed that part number 82730-35320 was right for my 2002 Limited with engine immobilizer, searched it in Google shopping, sorted by price, and picked the cheapest seller that looked like they might be reputable. It’s best to enter your VIN in the parts catalog to get a big green check mark before ordering, since vendors tend to refuse returns on electrical components. My part was this one, and ended up costing me ~$473 in 2017.
https://toyotaparts.bochtoyotasouth....ock-8273035320
The Toyota service manual does not have a specific procedure for replacing the junction block. I was curious to know if there would be any reprogramming after replacing, but it seems not. It took me about an hour and 20 minutes while chatting with a neighbor, cleaning panels before reassembly, realizing I was out of beer, etc. I did this:
- disconnect ground cable from battery
- remove screws holding gas door and hood latches
- remove 4 10mm bolts holding dash panel
- unclip electrical connections and remove cabin temperature sensor hose from dash panel stuff
- put dash panel in back seat
- remove long door sill panel – 4 phillips head screws, pull straight up until clips release
- remove kick panel – pull toward back of truck to separate from clips
- remove engine immobilizer wiring harness keeper clip, then remove harness plugs (2)
- bend left side dashboard panel to get to 10mm bolt holding upper left of junction block. Remove 10mm bolt holding bottom of junction block.
- Curse at an appropriate volume while wrestling the 39 (or 78, idk) plugs out of the back of the junction box. A couple of them require that you outsmart them by looking at the new junction box to see what’s keeping them stuck. After you know what to do, they slide right out.
- Yank out various other relays that are plugged into the box
- reverse course using new box
- connect ground battery cable
- fire up to make sure the engine is not immobilized and test all body controls
- test drive to scare up more beer and type furiously for a bit
- done
Linear Mode
