BEC/Starting Issue

[obxdude018]

I have tried the clutch switch by hand a few times with a no go, like I said all I have to do is smack the shit out of the BEC and it will then crank.

 

[obxdude018]

Oh I forgot to mention, the grounds that come out of the harness with the cooling fan(bolted under the upper radiator cover) were so incredibly hot that I couldn't touch it. So somewhere there is a ton of resistance build-up for it to be that hot.

 

[obxdude018]

Replaced the BEC and still a no-go, getting really frustrating and then it had to start to rain again.

 

[obxdude018]

Tested for power at the starter solenoid and no power when starting. I also put a jumper wire in at the clutch switch and that did nothing as well. I replaced the 10A fuse in the kick panel box also. Getting voltage to the clutch switch too

 

[obxdude018]

Ok I did a complete hack rewire, I bypassed the BEC relay system and put my own in (testing purposes), i ran a wire from the clutch switch to my relay and used the wire from the engine harness and left that hooked to the starter and voila she starts. My question does pcm need to know anything about the starting system(anti-theft and so forth), my problem has to be between the clutch switch and the pcm/bec connection.

 

[obxdude018]

No one has an answer.

 

[RocketcarX]

Maybe it's too late since you've bypassed the BEC, but how are the cables at the battery and leading to the BEC for power and ground? Also, if it was just as simple as the bad connections you were talking about, why not just bend the relay pins like other dude said and rock and roll? BAttery good? Alternator good?

 

[obxdude018]

I replaced the BEC thinking that was my problem, apparently not, it's somewhere in the signal wire that comes from the clutch switch and leads to the pcm/bec, I can't pull up the wiring diagram on my phone and computer from iihs.net for some reason. So all I did to see if it would work was make my own standalone relay which worked and the car cranks so much better as well. However the haynes manual(vague with their wiring diagrams) says the starting system does pass through the pcm, this is clearly a poor wiring connection or a short. If someone could tell me the wire color going from the clutch switch to the bec on a 05 v6 car (engine swap) or copy and paste it that would help me so I can do a proper resistance test. It's a violet/red wire leading out of the clutch switch, but my haynes manual says white/pink( like I said vague diagram since it doesnt get model year specific).

 

[RocketcarX]

If it starts so much better with your bypass mod, then I would think just test the circuit you bypassed. I mean, if you were able to identify it to bypass it wouldn't that be the one to test? Trace back from the BEC, should be the same wire all the way back to the clutch switch.

 

[obxdude018]

The only issue I had with that is if the that circuit passes through the pcm before the BEC then it could possibly change colors and without seeing a wiring diagram i wont be able to know if it does so. It really sucks since i have to guess at the wiring since my comp and phone suck.

 

[TexasBlownV8]

The "neutral bypass" is handled with the clutch pedal being pressed in; that has to occur to one of the PCM pins per wiring diagram. The other is PATS. Those 2 would affect the pcm engaging the starter.

Dont forget, the clutch as 2 switches, one n/o and one n/c; one for starter circuit, one for cruise control disabling.
In doing an auto to manual swap, if the clutch plug is not plugged into the stock harness, or the switch is bad, it wont satisfy neutral operation, and the pcm wont allow things to start.

 

[obxdude018]

http://iihs.net/fsm/?dir=40&viewfile=Starting System.pdf

 

[obxdude018]

Tested the white/pink wire going from the sjb to the bec and that wire showed no resistance, tested the green/yellow that goes from the bec to the pcm and that one appeared fine as well. Starting to run out if options

 

[TexasBlownV8]

You need to test voltage at 1 place first, and go from there: pin D12 of BEC connector C1035B, of PCM pin #2 of the middle connector (the LG-YE wire).
- When the key is on (not starting), there should be 12v at that wire.
if there is no voltage here, trace back through the relay to the BEC to fuse F21.
- Cranking, the voltage should go to 0 volts (if the pcm is internally-allowing the start to occur). if voltage stays at 12v or near it, the pcm is not energizing the relay coil and it wont start. If the voltage is going to 0 or close to it, the relay should be energizing and the issue is on the F4 side of the circuit.

I diagnosed this when figuring out a pats issue after a swap project.

 

[obxdude018]

You need to test voltage at 1 place first, and go from there: pin D12 of BEC connector C1035B, of PCM pin #2 of the middle connector (the LG-YE wire).
- When the key is on (not starting), there should be 12v at that wire.
if there is no voltage here, trace back through the relay to the BEC to fuse F21.
- Cranking, the voltage should go to 0 volts (if the pcm is internally-allowing the start to occur). if voltage stays at 12v or near it, the pcm is not energizing the relay coil and it wont start. If the voltage is going to 0 or close to it, the relay should be energizing and the issue is on the F4 side of the circuit.

I diagnosed this when figuring out a pats issue after a swap project.

I tested the green/yellow wire and it was producing 12 volts, I turned the key and nothing happened stayed at approximately 12 volts. Just want to verify I am testing the correct wire, its in the harness connector closest to the firewall in the BEC?

 

[TexasBlownV8]

Key-on verifies you're getting voltage to the pcm. You'll need to turn the key to see what happens in the cranking position, if it stays at 12v or drops.
You can test it at the bec connector, wherever you're reading the 12v now. It would not be near the firewall, as that circuit runs from the bec direct to the pcm down by them both.

Verify clutch pedal operation. check pin 33 at the pcm's middle connector, the lb-ye wire. With clutch pressed, it should go to 0 volts; released it'll go back up to 5 or 12 volts.
You can do this with just the key on, not cranking.

 

[obxdude018]

Key-on verifies you're getting voltage to the pcm. You'll need to turn the key to see what happens in the cranking position, if it stays at 12v or drops.
You can test it at the bec connector, wherever you're reading the 12v now. It would not be near the firewall, as that circuit runs from the bec direct to the pcm down by them both.

Verify clutch pedal operation. check pin 33 at the pcm's middle connector, the lb-ye wire. With clutch pressed, it should go to 0 volts; released it'll go back up to 5 or 12 volts.
You can do this with just the key on, not cranking.

Yea I was just referencing which connector it was, I know it was the one in the BEC, but I just wanted to verify that. The green/yellow wire I mentioned didn't drop off like you said it should, I will check on the other wire in the morning when I get home and can actually look at it.

 

[TexasBlownV8]

Cool; that's progress. The pcm is not allowing it to start. You got voltage there through the relay coil; that's good so far.

On the clutch pedal, there are 2 separate switches. One is for starter control (shown in the link to the wiring diagram you posted), the other is to disable cruise control (not applicable to starting), and can be seen here: http://iihs.net/fsm/?dir=40&viewfile=Speed Control.pdf

Are you using a manual pcm and manual engine/trans wiring harness? Doesn't really matter at this point, since you're able to start it with your bypass. Just asking because this has more to do with your wiring color comments; on an auto harness for starter enable, the wires are wht/pnk or red/vio, different for different year models.
For the clutch connector/wires under the dash, that shouldn't matter.

 

[obxdude018]

Cool; that's progress. The pcm is not allowing it to start. You got voltage there through the relay coil; that's good so far.

On the clutch pedal, there are 2 separate switches. One is for starter control (shown in the link to the wiring diagram you posted), the other is to disable cruise control (not applicable to starting), and can be seen here: http://iihs.net/fsm/?dir=40&viewfile=Speed Control.pdf

Are you using a manual pcm and manual engine/trans wiring harness? Doesn't really matter at this point, since you're able to start it with your bypass. Just asking because this has more to do with your wiring color comments; on an auto harness for starter enable, the wires are wht/pnk or red/vio, different for different year models.
For the clutch connector/wires under the dash, that shouldn't matter.

Everything is manual engine based, who knows it may be the clutch switch, I was doing a bypass on the clutch switch and using that as the trigger for my bypass relay, the haynes manual I have has the clutch switch right after the SJB so that's why I did it like that. However I looked for model specific wiring harness and see where it is triggered through the pcm.

 

[obxdude018]

This is the wiring diagram in the Haynes manual, it is closely the same as the online one, except this lists the clutch switch after the SJB for 05-06 cars. The thing that confuses me on this diagram is where it switches from blue/red to white/pink, wtf is that all about.