[UNISA JECS]

In order is see the 5v at pin 27 you have to depin the wire from the harness at the ECU to isolate the ECU from the Engine then with the KOEO you will see 5.12v, then thereafter everything connected with no short in the wiring and a good 560Kohm knock sensor you will see 2.5v, this is do to ohms law as was discussed earlier.....the knock sensor generates a small voltage depending on knock or lack there of and on to the 2.5v and depending on the variations of these voltage are certain conditions a code 34 will be entered i.e. like the 3.32v with KOEO if definitely problem because the engine is not even running to cause knock so a code 34 is entered because that's an obvious no brainer.

 

[Cheezit]

I agree that the 3.32v seems odd. I got the 3.32v when I had the KS connected to its harness but not grounded (unbolted from the block). I do not know how to explain the 3.32 number, but it does not seem like the number I should focus on.
When I bolted the KS back in place, the voltage was 2.02-2.03v. 2.02v seems like the number I should focus on, not the 3.32v because, as you point out, the engine was not running in order to produce a possible knock. I agree with what you say, that there would not be any increase or decrease in the 2.5v unless the engine was running and producing knock.

2.02 volts represents the voltage present with KOEO (and when running) and the KS is grounded to the block. The FSM says ~2.5v should be present.

After having replaced the KS, when I do the self-diagnosis, I do not have a code 34 on the ECM anymore.
I get the code 55, "no problems".
If the ECM is responsible for sensing knock and retarding the timing, a code 55 would mean it is not retarding the timing anymore, Right? (I am seeing 2.02 as close to 2.5.)
Do you think 2.02v represents a short even though the ECM is not throwing a code 34?

 

[UNISA JECS]

I agree that the 3.32v seems odd. I got the 3.32v when I had the KS connected to its harness but not grounded (unbolted from the block). I do not know how to explain the 3.32 number, but it does not seem like the number I should focus on.
When I bolted the KS back in place, the voltage was 2.02-2.03v. 2.02v seems like the number I should focus on, not the 3.32v because, as you point out, the engine was not running in order to produce a possible knock. I agree with what you say, that there would not be any increase or decrease in the 2.5v unless the engine was running and producing knock.

2.02 volts represents the voltage present with KOEO (and when running) and the KS is grounded to the block. The FSM says ~2.5v should be present.

After having replaced the KS, when I do the self-diagnosis, I do not have a code 34 on the ECM anymore.
I get the code 55, "no problems".
If the ECM is responsible for sensing knock and retarding the timing, a code 55 would mean it is not retarding the timing anymore, Right? (I am seeing 2.02 as close to 2.5.)
Do you think 2.02v represents a short even though the ECM is not throwing a code 34?

Earlier in this post is one is the reason I suggested running a wire of any kind for testing purposes from pin 27 to the knock sensor (grounded) and then from that you will see the default value and that will give you a good idea as to the condition of the existing wiring but you have to isolate the original wiring by depining it from the ECU.

As far as 2.02v its obviously on an acceptable range that the ECU deems as ok hence the code 55 so I would worry to much but I would monitor your codes as you keep driving just to see if you set of a code 34 after some aggressive driving preferable on a hot day.

 

[p10_swapper]

I just watched a video about multimeters. If the multimeter beeps when using the continuity function, there is continuity, and continuity means there is a good connection between two things, but there still may be a short, just not a broken wire. Beeps for continuity means the wire is sound, No beeps means no continuity and too much resistance along the circuit, which may mean there is a short or broken wire.
Based on this understanding, here are the KS circuit test results and interpretation.
after going back and reading this, it sounds like a broken circuit... I haven't read all the pages though...excuse me if you
1. KS Harness (terminal B) and ground: No beeps = No continuity = short circuit
2. Terminal 27 on ECU and ground: No beeps= No continuity = short circuit
3. Terminal 27 and KS harness (terminal B): No beeps = No continuity = short circuit or broken wire
4. Terminal A on Knock Sensor and ground: Beeps sounded = continuity = good KS

this post is describing a completely open/broken circuit. Honestly, I haven't kept up with this thread since page 2 though, so sorry if you all are past this

 

[Cheezit]

Earlier in this post is one is the reason I suggested running a wire of any kind for testing purposes from pin 27 to the knock sensor (grounded) and then from that you will see the default value and that will give you a good idea as to the condition of the existing wiring but you have to isolate the original wiring by depining it from the ECU.

As far as 2.02v its obviously on an acceptable range that the ECU deems as ok hence the code 55 so I would worry to much but I would monitor your codes as you keep driving just to see if you set of a code 34 after some aggressive driving preferable on a hot day.

Hot days may be gone now, but I'll drive hard and keep my eye on the ECM.
I was trying to avoid having to depin and risk damaging the ECM connector.
I do need to try the depinning test to be sure, but I don't know how the braided shield splits or connects to junction F19 you pointed to earlier. How does it connect at F19 junction, a connector? (If so, I do not know how to detach/ attach a shield braid to a connector.)

Is it difficult to re-insert the wire you depinned or insert the new wire on the ECM harness? Looks a little tough, which is why I haven't done it yet , hahaha.
(Home Depot did not have the specific type of wire you mentioned, and an electrical supply company only sold it by the spool.) Will any 18 gauge shielded wire wire work for testing?

 

[UNISA JECS]

Before you depin do a test just disconnecting the knock sensor and or knock sensor harness and check your voltage at pin 27 also.

Just strip a long piece of plain copper wire and shove it through pin 27 to make contact or you can simple cut the wire and solder it back after if you cant depin it. For testing you can uses regular wire it doesn't have to be shielded.

 

[Cheezit]

Alright!, great advice. I'll do the test you mention, and I'll see about depinning asap. I do not want to cut/ solder anything if I don't absolutely have to.

 

[Cheezit]

I disconnected the knock sensor sub-harness from two points (individually), testing the voltage with engine running, and got 3.31v both times.
When the sub-harness was connected, voltage was 2.02v, engine running.
With KOEO, these two values increased by .01v.

First, I checked the voltage present on the circuit with engine running ---->2.02v
Next, I disconnected the KS sub-harness, just to the left of the injector harness, then tested voltage-->3.31v.
Then, I reattached KS sub-harness, cleared the code 34, and tested voltage --> 2.02v.
I verified I had code 55, disconnected the KS from its connector and tested voltage ----> 3.31v.
I reconnected the sub-harness to the KS, cleared the code 34 and tested voltage----> 2.02v.

 

[UNISA JECS]

That's cool now depin pin 27 with KOEO and you should get 5.12v

And while your at it run a piece of regular wire form pin 27 to the knock sensor and bolt the knock sensor down that way it is grounded and see if you get something other than 2.02v, this will tell you if the existing knock sensor harness is faulty or on its way out. My hunch is you should get closer to 2.5v with KOEO.

 

[Cheezit]

Thanks for the guidance. I'll see if I can depin pin 27 tomorrow. I need to get a longer length of wire first.
How should I go about attaching the new wire to the knock sensor after having depinned pin 27? (I'm working solo.)

That's cool now depin pin 27 with KOEO and you should get 5.12v

And while your at it run a piece of regular wire form pin 27 to the knock sensor and bolt the knock sensor down that way it is grounded and see if you get something other than 2.02v, this will tell you if the existing knock sensor harness is faulty or on its way out. My hunch is you should get closer to 2.5v with KOEO.

 

[UNISA JECS]

Thanks for the guidance. I'll see if I can depin pin 27 tomorrow. I need to get a longer length of wire first.
How should I go about attaching the new wire to the knock sensor after having depinned pin 27?

I would just by some little alligator clips from radioshack and attach a length of wire to it and use that to attach to one of the terminals on the knock sensor.

 

[Cheezit]

I have the clips and the wire. I still have to look at the ECM harness connector to see it I will be able to depin pin 27 without damaging it.

 

[UNISA JECS]

I have the clips and the wire. I still have to look at the ECM harness connector to see it I will be able to depin pin 27 without damaging it.

Just make sure to left the "grey" gate and fashion a tool like I mentioned with pics in here and you should be good to go, cause I have practice I can depin a wire in seconds so you should be able to do it with a little practice, its not that hard.

 

[Cheezit]

This is such a great thread on knock sensor and related wiring discussion, I didn't want to start a new thread. I'd like to share my findings and fixes to my '92 G20 and the knock sensor code that my ecu was throwing. I was experiencing bad hesitation, then normal driving, then back to hesitation. It was driving me crazy.

Here's what I did:
1) Purchased new knock sensor from ebay, and placed it on the intake manifold. I left the old sensor in the stock location (didn't want to bother removing it, too much work).
2) Went to junkyard and pulled out that section of wire sub-harness that has the knock sensor wiring (if you want to see a pic of this sub-harness I can go get it if someone wants it). It's the same section that attaches to the starter. I originally thought it was the fuel injector sub-harness, but no, that's not it. Anyways, I carefully removed the wiring for the knock sensor and used it as my old knock sensor wiring is well corroded.

Check out the pic and you'll better see what I am talking about. You can see where the knock sensor wiring hooks up near the #1 fuel injector. After all the work, my car drives smooth again.

I noticed the grey connector that (just above the oil cap) comes off the left end of the harness (just under the knock sensor).
Is this the correct connector for the KS sub-harness? Earlier, I had been assuming it somehow supplied power to the fuel injectors.

I ask because oldman mentioned a "fuel injector sub-harness".
Earlier, he had mentioned that when searching for the KS sub-harness he had first assumed it was the fuel injector sub-harness.

When I was searching for the other end of the KS sub-harness connector, I assumed this male connector was the "fuel injector sub-harness", given its location and that it was the only connector that came off the harness running above the injectors.

However, after having replaced the Knock Sensor and eliminating the Code 34, I disconnected the grey connector I had assumed was the "fuel injector sub-harness", started the engine, gave it throttle, and it seemed to run fine. I checked the ECM, and it showed the Code 34. I reconnected the connector, cleared the code, started the engine, checked the ECM, and the ECM gave the "ALL GOOD" Code 55.
This makes me believe that the grey connector is not the "fuel injector sub-harness" connector, but the male connector that goes with the KS sub-harness. Could someone please confirm this?

 

[Cheezit]

Just make sure to left the "grey" gate and fashion a tool like I mentioned with pics in here and you should be good to go, cause I have practice I can depin a wire in seconds so you should be able to do it with a little practice, its not that hard.

When I disconnected the only connector coming off the harness that feeds the fuel injectors, the voltage increased to 3.32v and with it connected, voltage was 2.02v, which is closer to spec than the 3.32v was to 5v (reference voltage from the ECM). This seems to suggest that if there is a short, it is in the length of engine harness beyond the KS sub-harness. The ECM doesn't seem to detect a short though, so I am not really concerned with it. I don't want to risk screwing up the ECM connector, trying to depin it when I don't really need to. If the code 34 comes back, I'll probably consider doing it. Thanks for all the help. I do appreciate it.

 

[UNISA JECS]

Well all the info is in this thread to help you solve your problem, been her done this a few times.

 

[Cheezit]

Does anyone know which connector I have unplugged here? ----> http://www.youtube.com/watch?v=hxCOkOU6BsU
I had been thinking the female end was the end of the knock sensor sub-harness, but I have been told that there is no separate KS sub-harness on 91-93.5 p10's.
When I have it unplugged, the engine idles normal, the throttle feels/sounds the same, but I get the Code 34 Knock Sensor circuit code. Reconnect the connector and erase the code, and I get Code 55, all good.
I originally thought it was the injector harness, but if it were the injector harness, with it unplugged I would not expect the injectors to work. Am I mistaken in thinking this? Does anyone know which harness connector it is?

 

[UNISA JECS]

Your still on this, it's the knock sensor harness, its been a while since I messed with it on a B13 but how about getting a picture of the wire colors while your at it, this is basically the same connector on B13 SR20DE, S13 KA24DE IIRC.


The female end comes from the main harness side, the male end routes in the injector harness and braches off from there in a "T" fashion and down to the knock sensor is what im guessing just from looking at that quick video.

 

[Cheezit]

Thanks for confirming that it's the Knock Sensor harness. I had been hearing both yes it is, and no it is not. Confusing.
I found a picture of an after-market S13 KA24DE harness. http://www.wiringspecialties.com/connectoru.html
Looking at this part, it looks like the female end would be the end of the KS sub-harness, and the male connector is what connects it to the rest of the engine harness, at the injectors.

Your still on this, it's the knock sensor harness, its been a while since I messed with it on a B13 but how about getting a picture of the wire colors while your at it, this is basically the same connector on B13 SR20DE, S13 KA24DE IIRC.


The female end comes from the main harness side, the male end routes in the injector harness and braches off from there in a "T" fashion and down to the knock sensor is what im guessing just from looking at that quick video.

 

[Cheezit]

I AM REVIVING THIS THREAD TO POST A FEW RESULTS.
I am currently getting codes 12 and 34, MAF and Knock Sensors.
Engine barely runs.