Hey guys, I hope I'm not invading too much, but this place is a fountain of knowledge about TBI systems, and I'm out of ideas on my own.

I bought a TBI system from a guy on Ebay, and I'm installing it in my 350 engine that is actually in my boat. The system is from a 1993 Chevy 1500 5.7liter engine. The loom that came with the system was pretty beat up, because he had canibalized it, for what he needed for his carb, when he pulled it out.

Since the system is going into a boat, it's going to be an open loop system anyway, and won't have an o2 sensor, or any emmissions stuff.

What's left of the loom, is really all I need, except that the knock sensor wire is melted, and will need a new end.

Anyway, long story short, I've sorted out all of the wiring, and eliminated the unnecessary stuff, except for one remaining item, that I cannot find in ANY wiring diagrams that I've looked at.

It's a gray wire, that has a connector that looks very similar to a knock sensor connector, but this wire is gray, and the knock sensor wire is dark blue.

The other end of the wire was snipped at some point, and honestly, I can't tell if it ever went to the ECM at all...

Any ideas where this wire goes? I'm thinking maybe it was for an oil pressure gauge sending unit, but that's a wild guess. I've looked around for a secondary sending unit but they don't seem to be out there.

There HAS to be something like that though, because the oil presseure fuel shutof switch is just the two-wire switch, and doesn't have the pressure sender built into it.

Any help you guys could offer would be greatly appreciated.

Thanks!





EDIT: Sorry this is double-posted. I tried to delete this one, after I posted it in the electrical system, because I realized that was a better place... I can't delete it. My bad. Please don't shoot me!

 

looks like knock sensor. old fan switches had the same connector also.

 

so you've already solved your problem?

 

No, I haven't solved it, I'm trying to get a positive ID. Of this wire, from somebody who knows for sure.

It looks similar to the knock sensor connector, but it's not. The knock sensor has a blue wire, and it DID have a connector on it, but it's a bit melted...

 

it looks like the fan sensor connector. sure it from a truck?

 

+1 Fan switch themperature sensor connector.

 

+2

More info and a few simplified diagrams

https://www.thirdgen.org/forums/elec...elay-help.html

 

pocket is correct once your a member you have access to the wireing diagrams that your requesting

have fun

 

I just replaced my knock sensor since mine was disconnected. I found a wire like above but with a white wire not blue or gray, it only reached the knock sensor so I plugged it in (wouldn't reach fan switch no matter how much I pulled or re-routed), the car isn't running but did I maybe connect the wrong wire? I'm going to have to check this out. Seems much of my wiring was cut and replaced with odd colors making diagrams pointless to me.

IIRC someone on here made a thread with every connector, what it goes to and its wire color with a little picture of it and with about 3-4 inches of wire to show you exactly what it looks like. Hmm. Ill get back to you guys, maybe the wire is gray, but I am pretty sure its white, in which even if its gray I'm still wrong then?

I hate wiring.

 

Depends on what year your vehicle is, it's POSSBIBLE that it's a different color wire. It's also possible that the wire has been replaced.

The only way to know for sure that it's the correct wire, is to trace it back. use a multimeter, and check to make sure that the wire is going into pin E of your spark control module.

 

Turn the IGN on and see how many volts are on the wire. Itll be 12v or 5v

 

looks like my O/P gauge wire, just like it....

 

Ive never seen an oil pressure sender accept that connector on any make

 

This will help a bit I think for future reference.
http://www.repairconnector.com/categ...GR-CONNECTORS/

Knock/Coolant Sensor Connector
http://www.repairconnector.com/produ...-Pigtail-.html

Ill be checking my wiring, because then if this wire actually is gray and not white, I don't have a coolant temp switch or the sensor since the rest of my wiring is accounted for. I guess Ill be buying a hypertech switch and connector then.

 

Okay my wire is gray. So I found my fan temp switch connector. But guys...I have not one blue wire or any other connector like the one shown above on my car. My car ran perfect (besides overheating due to no fan, because the switch wasn't hooked up), without the knock sensor ever hooked up. Also, why would I not have a knock sensor wire anywhere? I literally have no blue wires on the passenger side of the wiring harness. Ill try and dig deeper but I'm not seeing it showing up.

Where would the knock sensor wire be coming from? Through the firewall or passenger side fender?

 

The knock sensor is not entirely necessary for the vehicle to run, it's just there as a failsafe, in case the engine starts knocking, it tells the ignition module to back off the timing.

The wire should be running into the spark control module (usually bolted on a bracket on the left hand side of the engine), pin E.

Locate the spark control module, find pin E, and trace the wire to its end. This is the wire that should plug into the knock sensor.

The engine will probably continue running just fine without it, but it's good to have, in case you end up with some crappy gas, or something else goes wrong, that might cause detonation.

 

Okay guys, checked out my wiring diagrams, the knock sensor wire is white on the TBI vehicles. I'm good to go.