Impending Vortec Swap (1 Viewer)

[slow95z]

you could always just put a switch under the dash or seat and operate the fuel pump that way. lots of friends have jeeps with hidden fuel pump switches to help prevent theft.

 

[DieselDriver]

What is the benefit of using the Toyota relay for the fuel pump?

 

[lazy]

this is perfect! now I know what to do with all the random stickers I get, stick em to the 2 year old....

They'll do the sticking. The 4 year old may have helped....

 

[bloc]

What is the benefit of using the Toyota relay for the fuel pump?

Most of the wiring is already in place, wired for the correct current, weather/vibration proof, and with toyota reliability.

Just have to find a good way to trigger it.

@lazy I did just have another thought. You could switch the polarity of the COR and trigger it pretty easily with existing wires. If you cut the black/blue wire going to it near the relay panel by the driver's feet and connect the black/blue going to the relay to ground, you can hook up the GM ECM DkGn/White to the toyota IH1 pin 17 and the GM ECU will now have control of the COR. The only potential glitch here is if there's a diode in that circuit, which would prevent reversing polarity like that.. but I don't see one on the diagrams.

Also make sure you shield the left over black/blue stub.. it will still have +12v any time the ignition is on. Also with the importance of this circuit I'd probably solder instead of using a tap.

 

[lazy]

IH1 17 to GND will let ignition switch control Circuit opening relay. Correct, but, potentially redundant and not the best way to go. ECU loses control of fuel pump relay.
E7 13 to GND will lock the "2-step" fuel pump relay into full-voltage mode. Correct. Personally, I'd rather bypass this relay and eliminate one point of failure, but what you propose ultimately would work.

GM ECM DkGn to E7 pin 12 isn't a good idea. The GM ECM is supplying +12v when it wants to turn on the fuel pump (via relay).. but the yellow wire is ultimately what provides the +12v for the whole fuel pump. Normally this is a big wire, controlled by the EFI Main relay, and can carry more than enough current (along with most of the sensors, like you mentioned). Your configuration would have the GM ECM supplying fuel pump current.. no bueno.

Since the toyota ECU switches the COR on by controlling GND, and the GM ecu switches the fuel pump relay on by controlling +12v, you have a little bit of trickery to do. Simple as installing another relay controlled by GM ECM to switch GND like the toyota ecu does.. but again, more complexity. I'm curious what other people with later model cruisers are doing with vortec swaps.

And for the record the Circuit opening relay is different on 93-94 trucks vs 95+.. so I don't think what rockrod did will work for you. Even then I'm not sure how it worked out.. seems like there's a wire missing that would control the COR and the GM ECM ultimately providing current for the pump.

Got it, that makes sense. You want the GM computer controlling the relay, but doesn't supply power.

Idea #6..... Basically using the EFI relay as the fuel pump relay. This relay works like the GM version. I've gutted everything else on that wire....

• Plug Y-R into connector EB1 near toyota fuse box, at the distributor.
• Reestablish connection Y-R at IH1, pin 22.
• Connect wires 2 (Yellow) & 4 (R-G) at the circuit opening relay by the driver's feet - bypassing the COR.
• Connect wires 5 (R-G) & 3 (R-B) at the fuel pump relay
• Connect GM dk green/white to E7/pin3/R/MRLY to switch on power when starting.

This should eliminate the need to ground wires, has the power source for the fuel pump coming from the fuse box and doesn't have me adding any wiring or relays under the dash.

What is the benefit of using the Toyota relay for the fuel pump?

To avoid running wires to the fuel pump is the reason I am trying to go through the toyota relay.

Most of the wiring is already in place, wired for the correct current, weather/vibration proof, and with toyota reliability.

Just have to find a good way to trigger it.

@lazy I did just have another thought. You could switch the polarity of the COR and trigger it pretty easily with existing wires. If you cut the black/blue wire going to it near the relay panel by the driver's feet and connect the black/blue going to the relay to ground, you can hook up the GM ECM DkGn/White to the toyota IH1 pin 17 and the GM ECU will now have control of the COR. The only potential glitch here is if there's a diode in that circuit, which would prevent reversing polarity like that.. but I don't see one on the diagrams.

Also make sure you shield the left over black/blue stub.. it will still have +12v any time the ignition is on. Also with the importance of this circuit I'd probably solder instead of using a tap.

This could work as well. I would still need to add in the power from the EFI relay to the IH1 pin 22. I also got some of the crimp/solder/seal butt connectors that I am using when connecting wires that should be permanent.

 

[bloc]

Got it, that makes sense. You want the GM computer controlling the relay, but doesn't supply power.

Idea #6..... Basically using the EFI relay as the fuel pump relay. This relay works like the GM version. I've gutted everything else on that wire....

• Plug Y-R into connector EB1 near toyota fuse box, at the distributor.
• Reestablish connection Y-R at IH1, pin 22.
• Connect wires 2 (Yellow) & 4 (R-G) at the circuit opening relay by the driver's feet - bypassing the COR.
• Connect wires 5 (R-G) & 3 (R-B) at the fuel pump relay
• Connect GM dk green/white to E7/pin3/R/MRLY to switch on power when starting.

This should eliminate the need to ground wires, has the power source for the fuel pump coming from the fuse box and doesn't have me adding any wiring or relays under the dash.

This looks like the best solution. If anything it's simpler than OEM toyota..



If you want good access to the Red MRLY wire EA2 connector under the fuse block would be a way to get it without having to open any (or at least very much) wiring harness. Alternately you can just go direct into the fuse block.. IIRC removing a little bit of tape and a zip tie allows you to open the bottom.

Don't know whether you'll need it, but if you go that route, while you are in the fuse block you can add terminals from a junk yard block to add circuits to the stock block. I had to do this to get the stereo working in my LX/LC hoddgepodge.. but added another and have a spare 15A wire coming out for the future.

 

[lazy]

Is the best place to put the GM computer in the battery box? I saw one of rockjock's videos on youtube has it in there....I was kind of hoping for an in the cab solution, but I know that thing is pretty big. Any weather concerns having that thing in the battery box? I kind of need to nail that down to finish building my harness. Going with fancy tight weave PET sleeving, heat shrink ends. Inspiration from the $1200 Chase Bays harness....

I plan to run a GM fuse block and build extra terminals from there. I'll start with the house size one, and then build another once I get this up and running.

 

[JeepinPete]

I did this swap in my old Cherokee. ECM was under hood, on the top of the inner fender. Plenty of time offroad, mud, rain, etc. No issue what so ever. GM mounted them under the hood, you know they made very sure that those waterproof connectors were indeed waterproof.

 

[alia176]

Had a wiring helper today .

View attachment 1308106

FINALLY, some knowledgeable help is found....

 

[DieselDriver]

LSX 24x DIY Harness Mod Kit

You could use this in lieu of using the big GM fuse box, it has fuses for ecm, left and right banks, fuel pump relay and fans (or not in your case)

It's a nice unit for the price all pre-wired
I used this on Stock GM harness that I stripped down to a 4 wire set up

 

[JeepinPete]

That is a sweet setup.

 

[lazy]

Spent the night tapping the stripped out threads from marks adapter. Note, they are very easy to strip. And you need a different length bolt behind where the high lo shifter bolts on. 30mm, maybe 35. I tapped to 1/2 20.

Tapped hydro boost return on power steering, threaded in bolt and welded in.

Found the fuel pump relay. It's driver side, Below the hinge for hood.

Wire colors are correct. And it says what it is, so not a biggie.

Can't seem to find the orc in the left kick panel. This is my best guess, but wire colors are off. I'll have to test for continuity tomorrow from the e7 connector.

And the only wire I cut that wasn't a ground...

 

[bloc]

That denso relay is for the starter interrupt on an alarm. Black/white is the primary starter signal wire. If you just remove it the truck won't crank.. though ditching that and the harness adapter is pretty easy while you are in there (if the alarm doesn't function anymore).

the COR should be one of the relays in the relay panel mounted in the lower a-pillar. I don't know which one it is on the panel though.. and wires will be going into the back of the panel so you'll have to loosen its mounting bolts to get a good look.

Edit: had a look at the 96 LX EWD.. appears the COR is a relay clipped to the bottom of that relay panel.

And now you've got me confused on the fuel pump relay. I distinctly remember finding what you did.. but also having to relocate that aluminum box next to it to get my rig to run. Now I need to figure out what that part is too.. yay OCD.

Edit 2: I knew it was related. That aluminum box with fins is the resistor that steps down voltage for the fuel pump when the FPR isn't activated. So technically you could leave the FPR control alone and just splice those two wires together and the fuel pump control circuit would default to full battery voltage even without power to the fuel pump relay.

For some reason that thing is moved on the later vehicles. Earlier it's on the other fenderwell.

 

[bulhas]

subd.....

 

[bloc]

Just had another thought..

You'd have to verify that the two relevant pins in the FPR are the same type.. but if so you could just switch pins 2&3 (red/white, red/black) at the FPR and the relay's default non-energized position would now pass through full voltage instead of sending current through the resistor circuit.

In case anyone isn't following along, the TOYOTA fuel pump relay doesn't actually turn On or Off.. when energized it simply switches from circuit A (normally has a resistor to step down voltage to the fuel pump to make it quieter) to circuit B (no resistor, full battery voltage). Switching these wires simply reassigns the circuits to the default circuit A no longer having the resistor. No energy needed at the FPR. And this is only possible because of the realization that the resistor is external to the FPR. I was misremembering that it was internal.

This would allow you to forget about needing to energize that relay, and no need to cut/splice/do anything that would reduce reliability.

And if the "fuel pump relay" not turning on or off confuses anyone (and they haven't been reading the walls of text I've been posting) in toyotas the "circuit opening relay" acts more like a traditional fuel pump relay.

 

[lazy]

pregunta....fuel level sender. I assume one of the issues resolved in the "Tune" is to adjust resistance levels of the fuel sender? or you just "delete" that part in the pcm and send straight to the gauge.

Since I need the entire evap system, I need the fuel level sender to route through the pcm to trip the EVAP as I understand it? Anyone know resistance levels of the toyota fuel level sensor?

Looking at going this route for the fuse block. I think I can fit 3 of them underhood (where old charcoal canister was and/or next to brake booster) and will have spare relays and circuits. DIY - Build and install a Bussmann RTMR Fuse/Relay Block

 

[lazy]

pregunta numero dos....fuel level sender. Anyone know how to adjust the resistance via circuitry? The state referee said I have to go in with totally stock programming, so I can't screw with the resistance levels in the pcm. A lot of options I can think of, including dropping tank and installing second sender, but there has to be a way to send the signal over to the pcm with a "black box."

 

[aktundra]

Looked at my friend's 2016 Silverado, and the GM engineers have his ECM in front, and facing forward !!

But it did seem to be placed so as to benefit from the cooling airflow of the rad fans.

 

[lazy]

Battery box it is. I need to change all my assumptions about what wires to tap though....

Found the circuit opening relay. You need to remove the foot rest and pop off the 3 clips holding on the kick panel.

Pretty sure it's the lowest one hanging off the relay panel.

 

[lazy]

Trying to make this brake switch work. Lights need switch to complete circuit, gm pm needs it to interrupt circuit. This switch does both. No fussing with relays and hood rat (the kind of wiring I do) wiring.

A little bigger than the gm switch, but I think I can make it work. $9.99 @ vatozone.

New switch is on the right....