help with toy truck tbi (1 Viewer)

[donnie12]

iv got a 1994 mini truck tbi 350 i bought it running then crashed it i had to replace the cab and now trying to re do the wiring i am having a hard time half the reason im having so much truble is because im looking at the original wire up and dont know what this guy did one thing he did was spliced into the temp sensor (yellow wire ) and put it on a switch he also spliced onto one of the fuel injector wires i bought a painless harness what do i do just feed power to the orange wire going into the ecu ? do i have to do any thing with the ingnition iv ben reading every where trying to figure this out and cant

 

[liljlandon]

Ill make a longer winded answer later. Heres my short one.
Hope that might help you.

 

[liljlandon]

Alright. Two of the Fuel Injector wires are always hot, so they are considered a switched negative (i think thats the right term...) so if he spliced into the HOT wire, he was probably just cutting corners. Now, as to the oil switch- GM wired it weird. IIRC, the wire was also wired into the Fuel Pump relay - I believe GM was cutting corners and if you werent getting an oil pressure, it cut the relay so you would have no fuel.

Heres another good resource- http://chevythunder.com/1227747_ecm.gif

FYI- Not many people here are into cross breeding, but I injected my 22R with a 4.3 Throttle Body as did YotaJosh (got the idea from him), and used a moates.net programmer. Thanks to YotaJosh, I had a running truck pretty easy. Without him... The headache would have been much larger.

 

[Combat Chuck]

you may have a better pool of info from the 40-series board, since a 350TBI's a commonplace swap for them.

 

[YotaJosh]

Find a junkyard (or even ebay), find a truck with the same motor, and buy the entire wiring harness from it. You'll be better off than trying to figure out how to marry that Painless harness with stock GM wiring with Toyota wiring, etc, etc.

Or, find a good wiring diagram and trace them out wire by wire, sensor by sensor. It will start making sense once you break it down into smaller parts and study how each part of the wiring works.

 

[Combat Chuck]

I didn't notice this part:

i bought a painless harness

nothing "painless" about it, those kits are the horrific spawn of crossbreeding a nightmare and a migrane. It's easier, and more documented, and cheaper to do as Yotajosh says and snag a used one from a yard, and call it a day.
There's more documentation on the stock chevy junk than any one aftermarket wallet-black hole.

Trust me, I tried Painless on my 40, long story short, when the time comes, I'll import a 70-series harness, and my dad and I will mod it to do what I need it to do.

 

[donnie12]

I didn't notice this part:


nothing "painless" about it, those kits are the horrific spawn of crossbreeding a nightmare and a migrane. It's easier, and more documented, and cheaper to do as Yotajosh says and snag a used one from a yard, and call it a day.
There's more documentation on the stock chevy junk than any one aftermarket wallet-black hole.

Trust me, I tried Painless on my 40, long story short, when the time comes, I'll import a 70-series harness, and my dad and I will mod it to do what I need it to do.

the wring harness dosent seem to bad i mean all plugs are into all the sensors now i just need to know what wires i splice into what im confused about the fuel pump theres a wire on the painless harness labled fuelpump do i use that to give power to the pump and if any one lived in ct and wanted to comehelp wire this thing up ill throw you some cash

 

[YotaJosh]

The only wires I have tied from Toyota to GM are...

-12v fused constant from battery to system relay for main system power
-12v switched from Toyota fuse box - Engine fuse is good for this. This will activate the relay named above
-White Tach wire from coil to black wire where Toyota coil/ignitor connected (if you want the tach to work).
-Wires from fuel pump relay to fuel pump. Yes, your Painless wires for this should be used. The ECM controls the fuel pump.
-Start signal wire from ECM to starter wire on starter so the ECM knows your cranking.
-Grounds, grounds, grounds!

That's really it. It should run with the above taken care of.

 

[liljlandon]

The only wires I have tied from Toyota to GM are...
.
-Start signal wire from ECM to starter wire on starter so the ECM knows your cranking.


That's really it. It should run with the above taken care of.

So, this can be bypassed. Cause I did, somehow. Im pretty damn sure, which worries me. I'll look tomorrow to double check... But I'm not throwing codes, nor am i experiencing anything weird besides 'throttle follower'.

EDIT: My wiring is different than a normal TBI. so Donnie12, disregard my lack of a start signal wire.

 

[YotaJosh]

So, this can be bypassed. Cause I did, somehow. Im pretty damn sure, which worries me. I'll look tomorrow to double check... But I'm not throwing codes, nor am i experiencing anything weird besides 'throttle follower'.

EDIT: My wiring is different than a normal TBI. so Donnie12, disregard my lack of a start signal wire.

You don't have to run the wire all the way down to the starter. You could find the crank wire in the Toyota harness in the dash and tap into it there.

The cranking signal is what tells the ECM to start firing injectors, turn on the fuel pump, and set the base timing so the engine will start.

Edit: are you running 12v constant (say from the pink wire) to this pin in the ECM? That might cause some weird issues if so.

 

[donnie12]

The only wires I have tied from Toyota to GM are...

-12v fused constant from battery to system relay for main system power
-12v switched from Toyota fuse box - Engine fuse is good for this. This will activate the relay named above
-White Tach wire from coil to black wire where Toyota coil/ignitor connected (if you want the tach to work).
-Wires from fuel pump relay to fuel pump. Yes, your Painless wires for this should be used. The ECM controls the fuel pump.
-Start signal wire from ECM to starter wire on starter so the ECM knows your cranking.
-Grounds, grounds, grounds!

That's really it. It should run with the above taken care of.

"12v switched from toyota fuse box " is that the 80a fuse

 

[YotaJosh]

"12v switched from toyota fuse box " is that the 80a fuse

My truck is older (79-83) so I don't have the large fusebox under the hood, so mine is tied to an engine fuse (20a) under the dash. The 80a one might work for you.

Any 12v source that stays hot when cranking is fine for this. If it turns off during cranking (like accessories, radio, etc), then you can't use that circuit.

 

[donnie12]

i got it running but i have to pour alil gas in the throttlebody at first i dont know what wire is the cranking wire

 

[YotaJosh]

Answer is in the attachment on post #2.

It's the purple/white wire that goes from the ECM - pin C9, to the starter engage wire.

 

[donnie12]

ok last question on the fuel pump relay theres a red wire coming off of it with a connector, i see the diagram but i dont know what to do with

 

[liljlandon]

I left it unhooked, not sure thats the right way... yotajosh prolly knows!

 

[YotaJosh]

ok last question on the fuel pump relay theres a red wire coming off of it with a connector, i see the diagram but i dont know what to do with

It's a diagnostic wire. When you connect it to constant 12v power, it engages the relay so the fuel pump will run regardless of key position or ECM.

It's used to test the fuel pump. The ECM only runs the pump for 2 seconds on key up until you start it.

Cliff notes: you can ignore it.

 

[liljlandon]

It's a diagnostic wire. When you connect it to constant 12v power, it engages the relay so the fuel pump will run regardless of key position or ECM.

It's used to test the fuel pump. The ECM only runs the pump for 2 seconds on key up until you start it.

Cliff notes: you can ignore it.

Brilliance shines upon ye!