Project 2ZR Vios, part Deux!

[CrankyOldMan]

This was much simpler than I thought it would be. It did involve dropping the fuel tank to get the first hose out and the (unnecessary) removal of the filler neck. No pictures, it's just undoing a few bolts and hose clamps. The hard line that goes to the purge valve in the engine bay had to be cut in order to get it out from the firewall area because it was tangled up with the brake and fuel lines.

To close off the hose barbs, I got some 3/4" and 9mm silicone caps from McMaster. They came in packs of 5 and 10 respectively so I've got extras. Silicone should be immune to deterioration from the gas vapors and won't dry rot--looking at you, rubber. I've ordered some pinch clamps for the tank vent since it's going to be relatively inaccessible and I don't want to worry about it coming loose.

[CrankyOldMan]

Probably overkill and pointless but figured I'd address it since I (also needlessly) removed the rear brace to drop the fuel tank. The bolts and washers that were installed on it looked like they could use an upgrade. The bolts were 8.8 (~grade 5 for us Imperial types) but the washers were too thin. The openings at the bottom of the "tubes" on the brace are huge. Not sure what kind of manufacturing tolerances they're working with but they're definitely oversized, hence the deformed washers with a non-flanged bolt.

Went to the local Ace hardware and grabbed a few grade 10.9 M8-1.25 x 20 flanged bolts and some hardened M8 oversize washers. They fit fine but the washers are still a little thin and the bolt heads are 13mm. Savages and their 13mm wrenches, I tell you what.

So I went to McMaster and looked up some more skookum washers and found that their flanged 10.9 bolts were 12mm heads. Great success! The hardware store washers were ~2mm thick (.080"), the bigger ones are about 2.8mm (.110). It was a snug fit and I had to loosen both sides to get all four bolts in. They still protrude a bit into the fender well, so I may grab some 16mm bolts with my next McMaster order.

I won't know if there's a difference in washer strength until I do some field testing, hopefully they will fare better.

[Neinris]

It's funny that you got rid of your evap canister, when I was struggling months ago looking for a replacement to get rid of a ghost fault that's not even throwing me a CEL.

I don't think the strength of the washers matters for the rear arm brace, those things weighs what like a pound? It's the strength of the bolts that you need to worry about more, if they're able to withstand any of the flexing.

If you're trying to reduce weight, why not ditch the washers as well.

[CrankyOldMan]

I stumbled on an "inertia activated fuel pump shut-off switch" today and thought it might be worth investigating how the Yaris deals with cutting power to the fuel pump in the event of a collision. Some OEMs use a manual-reset mechanical switch to interrupt power to either the pump (low current applications) or the pump relay coil (high current applications).

After some very confusing and misleading searches, it turns out that Toyota used to use the Vehicle Air Flow (VAF)--precursor to the MAF--sensor or the ECM to control the fuel "circuit opening relay", as shown in the attached illustration. The Yaris has two relays between the ignition switch and the fuel pump: IG2, which is energized by the ECM and C/OPN, which is energized when the key switch is in the ON position. I didn't understand what the abbreviation "C/OPN" was until just now--it's Circuit OPeN. Aha!

The funny thing about this is that the Yaris ECM doesn't control either of these relays--it only controls the EFI Relay coil. The EFI Relay does provide power to the C/OPN contacts so the ECM can effectively turn off the pump by de-energizing the EFI relay. It's possible that the airbag ECU can send a signal to the ECM and tell it that a collision has occurred but it would have to be via CAN bus. All of the airbag components have been removed so even if it comes from there, I don't have a way to generate that anymore.

"So, Cranky," you ask, "what does this mean for your efforts to simplify the wiring?" Well, I'm glad you asked! I want to remove the interior Junction/Relay Block because it's largely useless at this point. Its primary purpose is to manage the in-cabin convenience items, almost all of which have been deleted. There are two relays on/inside the block that are still used though: IG1 and C/OPN. I think that replacing the C/OPN relay will be pretty simple, I just need to measure the current draw to size the relay. IG1 is much larger but some of the things it supported are no longer installed. Probably going to take a bit of tinkering and measuring to sort that one out.

The attached schematic shows just the fuel pump and its related components. Took a bit of head-scratching to sort out how it's all connected and hypothesize how it works. Steps 4-8 will have to be determined empirically, I suppose.

Adding an inertia switch to the circuit has pros and cons though: increased safety in the event of a crash but increased complexity of the circuit and another potential point of failure. Hmm...

[CrankyOldMan]

After lots of frustration and mangled connectors/pins, I finally found some real info on how to remove the smallest pins! There's an OEM wire harness repair document that seems to have all the info I was looking for. It lists the type, size and quantity of terminals for each connector suffix and repair wire part numbers too. I.e. Yaris connector D6 "Windshield Wiper SW Assembly" is part number 90980-12359; suffix 12359 has 4 ea. 0.64 II and 6 ea. 2.3 II female terminals; repair wires are parts 24290 and 12340 respectively.

Props to the author of this article for buying the OEM tools and writing up a review!

Important details:
* Most terminals can be removed with the 1mm-wide tool described in the Yaris EWD. I got a Molex 0638138600 from DigiKey for removing pins from an OBD-II port, seems to work just fine on 90% of the pins I've encountered. At ~$25 it was a steal for an OEM tool.

* Pins used to be sized by decimal inches, now they're metric. There are two different types of some terminals, indicated by "II" after the size. I.e. 0.025 inch pins are now 0.64; there are type 0.64 and 0.64 II, which use different removal tools.

Notes on the 0.64mm terminals:
* 0.64 terminals are most likely TE/AMP/TYCO sourced and are used in sealed connectors like the ECM, evap canister, occupant classification ECU, etc. Some of them may be available through online electronics components distributors like DigiKey, Mouser, Farnell, etc.

* The Toyota OEM parts for removing 0.64 terminals are really expensive:
- 09991-00500 (female terminal) is ~$115
- 09991-00510 (male terminal) is ~$160

* The connector OEM (TE Connectivity) tools are more reasonable but still expensive:
- 1276565-1 looks like 09991-00500, ~$70
- 1579007-8 looks like 09991-00510, ~$90 ** Don't get 1-1579007-8, that's for round terminals in a different connector!**
- 4-1579008-5 also looks like -00510, ~$90

Notes on the 0.64 II terminals:
* 0.64 II terminals are probably Sumitomo sourced and are used in non-sealed connectors. Sumitomo doesn't have any retail/customer-facing options so you're probably not going to get them direct. Take a look around for race car wire harness parts suppliers and see if you can match pictures of what you need.

* The OEM part for removing 0.64 II terminals is also fairly expensive for what it is--a piece of flat spring steel with relatively tight tolerances.
- 09992-01030 ~$55

* Edit: Great picture of a hybrid 0.64 + 2.3 connector on atomic_hoji's 2ZR swap thread!