PSI Conversion
 

I have a PSI conversion wire harness in my 68 Camaro with a T56 trans.
Engine LS3
Do u need to have the brake switch hooked up? I cannot get the car to fire, and the guy who wired the car didn't hook up the brake switch. Any ideas?

Not only do you need it hooked up but you need a modern switch... Car won't crank without brake petal depressed

http://www.psiconversion.com/tech_ar...STRUCTIONS.pdf

Thank you I figured it needed to be wired.

Keep you posted

I thought the TCC (Torque Converter Clutch) signal was only needed with the auto trans. At least that was the case with the LS1 builds I did.

Is the car cranking? Is there provision for a clutch safety switch in the harness?

A lot of guys make the mistake of connecting the ECM power to the power that is not hot when cranking. It needs to be connected to power that is hot both when cranking and running.

Don

Put a new cam sensor in still not fire.

^^^This...

Andrew

I used PSI and had a firing issue too due to the tune and VATS. I had to add a wire to the harness and put it to constant ground. I forget exactly which one it was but will see if I can find it tonight.

You can and google it to come up with the wire, that's how I figured it out.

Do you have fuel at the rail?

Yes fuel at rails. I did notice the power dropped from 12v to 9.8V when cranking so I'm charging the battery. Maybe the ignition switch could be bad also. Trying to figure this out.

When cranking, do you have spark?

No spark

Then you must have a fuse blown in the PSi fuse block or you might not have correctly wired 12v to one of the wires necessary. If I remember correctly, there is a red wire that requires positive all the time and another wire that is specific to the fuel pump. Since it doesn't fire and die quickly, the fuel pump relay is probably wired correctly. The thick red supply wire may not be. Double check this wire. I think it goes directly to one of the relays. I'm relying on memory so hopefully I'm remembering all this correctly.

It should be terminal 85 on the relay opposite of the fuel pump.

I checked that and it's working on key on and cranking. Think maybe the volts being low might of been it. I'll test it in a hour again

Volts drop down to under 10 while cracking. Not sure what the problem is ahhh

I think that'd be fine to start it. Was VATS disabled?

Where are you measuring that voltage drop at?

At the red wire that comes off the fuse box also another hot wire. I bought the harness from a forum member maybe they weren't deleted. I'll call PSI Monday

VATS delete is in the tune, not the harness. If it is not deleted, it will start and run briefly.

Don

Sorry I meant ECU and Harness

If you hooked up the 12 volt switched to the original wire that runs to the coil and it was older style points ignition the coil wire will have a resistor built limiting voltage during run.

I've never heard of a brake light switch wired to the ECM when using a manual trans that would prevent it from starting. Only time I've seen it was to make the reverse lock out work like stock.

Try wiring the switched 12 volt to 12 volt constant just temporarily to see if it will fire. If it does disconnecting the wire will shut the computer down and shut off the engine.

From what I've read a bad cam sensor will not shut the engine down but a bad crank sensor will.

With a PSI harness you do not need a brake switch with a manual.

If you wired in a neutral safety or clutch switch it would not crank so thats not the problem.

When you first turn the key on you should hear the fuel pump run for a few seconds. That would indicate the fuel pump relay is working.

Then you need to determine if the ignition relay is working. The easiest way is to touch the relay and have someone turn key on to see if it clicks on.

The other common issue with not starting is the ground wires that attach to the head are either not connected or loose.

I ran a constant hot wire still nothing. Fans come on right away I heard that means theres a code. Shipping the ECU out to PSI today. This will be the best thing to do as they can program it to my specs.

Did you pull codes?

I had the same issue with the fans and the harness/ECU I used on my LS7 Build from PSI. As I recall the fan set up was set wrong in the ECM. I have HP Tuner and was able to correct it.

One thing that can make the fans come on (provided the ECM is configured properly for all else) is not hooking up some sort of check engine light.

I recommend a low cost code scanner if you don't have one. Get one that lets you reset codes too. Very handy for these swaps.

Don

I have a scanner it will no link to ECU.

Tried everything lol.

My scanner wouldn't link when a fuse blew on the PSi harness. Changed the fuse and everything worked.

Damn, you at least get A for effort.. :)

Don

Checked all the fuses 5 times or more ha. I wish it was simple something so simple. Prolly is

What about all your grounds? How is everything grounded?

Don

Do you 'feel' the other relay click when you turn the key?

I have grounds all over the place. I will see what PSI can come up with later this week. Hopefully it is my wiring or something easy. They will make sure the ECU is programmed to my specs.

Heavy grounds from the battery to the block and body? Ground strap from the block to the body? ECM needs a nice clean ground.

Don

I have a heavy wire straight to the block. then Ground to the Subframe. I have sold mounts on the subframe.

Only thing it could be maybe I need a better clean ground to the body.

The ECU is grounded to the body.

This might be a clue......

You need to constant hot to the PCM, fused from the battery. The you need your keyed hot(which you have already verified). Once you plug in your scanner and turn the key, you should be able to connect to your PCM. If not, either the OBD connector is not wired correctly, or you don't have computer power, i.e., computer not booting up.

Your OBD connector should have a hot wire from the keyed hot and then a ground. The other wire goes to the PCM. You can check the pin with a volt meter once you turn the key on and see if there is power at the OBD connector.

That is what I would check first.

T,

That is why I asked if the other relay 'clicks'. It is possible the feed to one of the terminals from the back has come loose (possibly at 85). Also possible but rare is a bad relay. This connection is made by the end user with a provided female terminal.

See pages 13 & 14 here for some specific info:

http://www.psiconversion.com/tech_ar...structions.pdf

There is normally a good thick braided ground from the block to the body. The ECM is normally grounded to the block in the factory harness if I remember right.

Don

Thanks for all the feedback everyone. I will let everyone know what they say when they get to it. I will go over all my grounds tonight. Maybe add a few more.

I will keep everyone posted.

See steps 5.7 through 5.9 on page 7 for detailed grounding instructions for your harness:

http://www.psiconversion.com/tech_ar...structions.pdf


Don

I had 2 PSI computers that had the VAT's removed but...there was a security feature that was not turned off. Would crank but no fire

Does it fire with a little air intake cleaner sprayed in the throttle body?

Injector pulse?

That is my guess.