99 SR-5 2.7 5 spd- cranks but won’t start

the power flow should be as follows, with the key "ON" the EFI relay closes and +12 volts is provided to the White/Red(W/R) wire on the EFI relay. This W/R wire goes first to a splice in the harness with 2 legs. one leg provides + 12v to the evap VSV. The second goes to a connector in the left kick panel. This connector has some 20+ wires in it. The W/R wire then feeds the J/B 3. J/B 3 is behind the instrument panel with 6 harness connections. The W/R wire is split inside J/B 3 and it is this W/R wire that feeds the circuit opening relay. The PCM only grounds the control side of the circuit opening relay. With a test light hooked up to ground you should be able to energize the circuit opening relay by touching the Green/Yellow wire.

 

computer never puts 12 volts to anything. that's why everything it controls is run on relays. this way it can control many things without having 200 amps put through it. it gets 12 volts from the battery as you described but it never routes current directly to something like a fuel pump or lights or what have you. despite your code i don't think you have a pcm problem. i would bet it has something to do with that pump that was replaced.

 

OK. So let’s say I do this and I do indeed hear the relay pull in when I touch the G/Y wire with a test light hooked to ground. Would this then mean that I’ve got some sort of issue on that W/R wire in between the EFI relay and the COR? If that’s the case, I guess I just need to backtrace from the COR along the path you described and see if I can find an issue somewhere in that path on the W/R wire.

 

Ok so it sounds like the value of 1.2 V that I see on the W/R coming out of the PCM isnt necessarily a bad voltage value. Being that with both PCMs installed, I see this same voltage, I’m inclined to think that’s a normal value.

Since I was able to jump voltage straight from the battery to the blue wire at the COR and I heard the pump kick on and continue to run when doing this, I feel pretty confident that the issue is not with the pump itself. That should have confirmed that the wiring between the COR and the pump itself is in working order and the pump is working as well. Would you agree?

I really appreciate you guys helping me on this, I feel like I’m close, just need to keep plugging away at it.

Keep the suggestions coming! I’ll keep reporting back as I continue to check things off the list.

I’m wondering too if I need to check the wiring that runs from the crank sensor to the PCM. The crank sensor itself tested good, but perhaps there is an issue somewhere in the wiring between the sensor plug and the PCM.

 

Yeah you're on track and you've got good skills for this. I'm not much help but I'm cheering you on man. I want you to get this!

 

it is easier to understand looking at the diagrahm... I wasnt at my PC when I posted the above and did not have access to the electronic manual(s) to upload an example. This diagrahm is for a 2002 but it is essentially the same as the 1996 diagram that I described above. Essentally the EFI relay closes and this powers everything. Simple enough to check for voltage where it is supposed to be.

 

Thanks for that! The Haynes manual I have has a really nice diagram in the back too. I’ve been studying that for a while now while sitting on the couch and I think I should look at that J/B 3 and the connector in the left kick panel. Following that and what you’re saying about how the EFI essentially powers everything makes me feel that way.

One thing I already know is that I have 12v at the W/R wire where the EFI relay plugs in.

So if I follow the W/R wire in the diagram in the manual, starting at the EFI relay, I see the splice you mentioned where one end goes to the EVAP VSV and then J/B 3. So I feel like something is potentially loose or broken at J/B 3 or that connector in the kick panel.

I should basically be seeing around 12V on any W/R leaving J/B 3 right??

Since I understand now that the PCM isnt really applying the 12 V to the COR, I feel like I should indeed be seeing close to 12V at the W/R wire to the COR. Seems to me that something in the wiring, at the connector in the kick panel, or J/B 3 is just not allowing that to happen.

I think I’ve got a pretty good grasp of what to look for now.

I haven’t tried what you suggested with the test light at the G/Y wire, but I will. Is this just basically proving that the relay is pulling in like it should when grounded?

I did check that the G/Y wire has continuity between the PCM and COR and I was seeing 1.9 Ohms.

Thanks for all the help so far, I’m feeling pretty confident again that I’ll get this sorted out soon!

 

Did you ever figure this problem out? I'm having the exact same issue and it's driving me crazy.