Knock Sensor Wires

[just_passed_you]

I recently bought another hooptie. She's a 91b. 6/4 bolt combo. The link threw bad TPS, Knock Seneor code, and my personal favorite... 02 sensor isn't oscillating whatsoever. We look around the engine bay to find (surprise surprise) the whole wiring harness has been hacked into.

Step one we swap the knock sensor with a known working sensor.
We clear the codes, fired her up and she still flipped the TPS and bad Knock Sensor.

So we look to see if wiring is messed up.
It's now obvious someone has been here before. Wires from the plug are crimpped together with wires from the harness with colors that don't match up.

The knock sensor connector uses 1 black and 1 white wire. The wires from the harness that it's connected to are 1 green/back stripe and 1 blue/yellow stripe. WTF

Using Micehell OnDemand we printed out the wiring schematics and it only shows the 1 black and 1 white wire from the sensor, all the way to the ECU. This leads us to believe that either Mitchell OnDepand is wrong and the green and blue wires from the harness are just crossed or Michell OnDemand is correct and we should be looking for a white and black wire.

We switched the wires, cleared the code, fired her up and she still flipped the TPS and bad Knock Sensor. (now we notice that it reads 9 counts of knock when we apply fuel)

Without tracing from the ECU to the sensor does anyone have any suggestions on how to figure this out. Or does anyone happen to know of hand which wires should go where? Please and thank you!

 

[turboglenn]

Damn, i just dug out all the "notes" and diagrams that i have collected on DSM's and i have teh wire locations for a 2g at the ECU plug, but no 1g. But, i did find it on VFAQ ( they don't havea a good 2g ECU pin out list ) but their 1g is excellent.. go here to figure out what wire goes to what...BTW, all the sensors are tied to a common ground at the ECU NOT the chassis. So you can split into any other sensors ground or follow it to teh main "split off" of the grounds.

Electrical isn't that bad when you know what wire you're chasing.. It's when you have to ask "i wonder what wire might be keeping "X" from working?" then it gets to be a pain. I've rewired full cars for racing and once you get teh basics down it's pretty easy actually. The hardest part is finding places to run "extra" wires if you still have the stock harness and ECU in the car.

Here's the link

 

[just_passed_you]

From what I've been told and can tell from the wiring diagrams, the wires that are connected to my knock sensor should be the wires for the EGR Temp Sensor... thrilling! Even better, I can't find the EGR Temp sensor. (I know where it should be)



I'll get a better look this evening, besides.. nothing is MORE FUN on Christmas Eve than pulling your hair out.

 

[turboglenn]

Here's the wires on teh car side of the plu.. they differ on the sensors plug in color only.

The ones i remember off the top of my head are for a 2g car and that is as follows: Red = 12v for o2 heater - Yellow w/ red stripe is heater ground..It does not matter which of the 2 heater wires gets power or ground, they just both have to be hooked up This wire went bad on my car so i "T" off this wire and connect it to battery ground to make it work on my car.. Yours should be good, i hacked the ehll out of my harness for a stand alone install. Andyway to finish for you, White is "signal" and black is "signal ground"..this grounds at the ECU, NOT shared with chassis ground ( at least directly anyway) this is to avoid "noise" in the sensor's signal

 

[steve]

Even better, I can't find the EGR Temp sensor. (I know where it should be)

Unless you have a California spec car or '94 you shouldn't have a EGRT sensor. The federal spec cars just had the connector taped to the loom on the back side of the block.

 

[just_passed_you]

I decided to take a better look at things.

First, there isn't an EGRT sensor anywhere, no plug taped to anything and no place for it on the EGR Valve. I see what you're talking about though. On the other 91 there is a plug, using the green/black and blue/yellow wires and it isn't attached to anything.

I'm still at a loss for my black and white wire to the knock sensor. The sensor directly next to the knock sensor looks even more messed up than I had originally thought. Notice this one brown wire feeds 3 white wires.... Both sensor plugs pictured. WTF

??????????

<img src="http://www.arctic.net/~r_morgan/DSM/wires1.jpg"></img>

 

[just_passed_you]

Is it possible that someone decided to hack in a N/T wiring harness in my ride by using the EGRT sensor wires to connect the knock sensor? I don't see a knock sensor on the N/T rides so I'm quite suspicious at this point. Help! And look at that one brown wire that's connected to that mess, what the hell is that???

Non Turbo:
<img src="http://www.arctic.net/~r_morgan/DSM/nonturbo.jpg"></img>

Turbo:
<img src="http://www.arctic.net/~r_morgan/DSM/turbo.jpg"></img>

 

[turboglenn]

Man, you're still sorting this thing out? Whew, i hope you get it right soon, you've probably racked up some hours in the books and tracing wires by now. I'm not sure about an ECU swap from an N/T, but i have seen wires change colors on certain years. unfortunately i don't know a ton about 1g wiring, since the wires are usually heat cooked and brittle, unless the customer wants their aftermarket ECU routed through the stock wires, i hack most of the stock engine's harness out and replace it with the new ECU's harness. Even the 2g's that come to me are starting to show up with "brittle wire syndrome" to where i have to hack things back 6-10'' and run new plugs a lot of times.

 

[just_passed_you]

I guess all I need to know at this point, is what's missing from a turbo to non-turbo harness. I'd also like to know what the hell that one brown wire to 3 white wires thing is.

 

[Lonnie gandee]

I had a fwd 91 that was converted from a non turbo auto, to a turbo 5-speed..

It threw the same code, for knock sensor. 9 counts also.. At the sight of gas, instant 9 counts.

I bought a new sensor.. No go. Then i got to looking at the wiring harness. I knew it was hacked up, but never really looked to hard...

It ended up being, the knock sensor wire was spliced into the wrong wire in the ecu... Cuase non turbos dont have knock sensors, that was one 5 or so wires that needed switched around or spliced in..

Hope that helps.

 

[Lonnie gandee]

They gray plug look slike knock sensor...

Need a better pic of the other....

 

[just_passed_you]

The other clip (not the knock sensor) is a totally different plug. Looks like the clip that resides on a stock air filter can which is the BCS connector if I'm not mistaken. Anyhow, in the picture the clip next to the knock sensor is fed by 1 brown wire. You can see how they divided that one wire into 3... looks very odd.

Last night I got into the ECU connection clips to see if anything was messed up down there. The good news is that everything is in it's right place down there. The bad news is that everything is in it's right place down there....

White wire on the ECU clip for knock sensor, still MIA in the engine bay area wire harness. The good news (I suppose) is that the ECU grounding wire is green with a black stripe. That's one of the wires that should work if I were to tap into it for the knock sensor ground... (I think)

I'm going to unwrap even more of the wire harness tonight to see where in the HELL my white and black wires are for the knock sensor. If I can't, I'll be runing 2 new ones from the ECU, through the firewall, and to my knock sensor. That seemed like the easiest solution in the first place but I'm so anti-mess I don't know if I could stand it.

being there is so much interest in this thread.... I'll keep you all posted. Please, if you're reading this and have gone through something similar let me know! I appreciate all the feedback you guys have given!

*crossing fingers I'm really not dealing with a N/T harness*

Thanks!

 

[steve]

Keep in mind that your looking for a shielded wire for the knock sensor.
You'll want to use one if the pull your own wire.

 

[Lonnie gandee]

I would just jump the wires and see if that solves it. I just grounded his in the engine bay, and only had to splice one wire onto the ecu.

Here's an easy diagram, I'm sure yo have one though.

http://www.dsmtalk.com/gallery/data/500/Drawing2_Model_1_.jpg

 

[vernvision]

Solder your wires and seal them with shrink tubing! Butt connectors are just what they are S#@$!!! If you need better wiring diagram pics let me know I just posted some from my 92-94 Mits service manual.

 

[just_passed_you]

Almost every single wire is frey and brittle where it joins the clip. One clip just fell off. The whole harness his hosed and at this point I'm ready to just yank the whole thing out of the car. I found a complete harness for ~$300.

Is there an engine managment solution out there that would allow me to delete the entire harness and run aftermarket sensors? From what I've read so far, the AEM EMS uses the stock sensors.

Haltec?

Thanks


(PS I wasn't the guy who used but connectors, I thank the previous owner for that bit of genius)

 

[just_passed_you]

I just got off the phone with a guy named David at Haltech. (Apparently he's a former DSM'er) My questions have been answered! The whole wiring harness is getting ripped out tonight!

I can still use a few of the stock sensors and don't need the clips.

w00t!


I bet I could have made this work as-is and I appreciate all of the help,
I just can't see myself doing a bunch of work to replace stock
components with things that aren't aftermarket.

(I'm an aftermarket whore)

Cheers!