Here is my situation. My car throws a knock sensor code if I run my obd2 b18c motor with an OBD1 p72 ecu. However, my car don't throw a knock sensor code if I run my obd2 b18c motor with an OBD2 p72 ecu.

 

OBD2 knock sensors work fine with OBD1 ECUs.
check your conversion harness, make sure that the knock sensor wire is populated.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Relic1 &raquo;</TD></TR><TR><TD CLASS="quote">OBD2 knock sensors work fine with OBD1 ECUs.
check your conversion harness, make sure that the knock sensor wire is populated.</TD></TR></TABLE>

I'm not using an ecu conversion harness. I forgot to mentioned that my car is a 95 civic hatch and the engine is a 97 gsr. What do you mean by populate?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eh2 &raquo;</TD></TR><TR><TD CLASS="quote">

I'm not using an ecu conversion harness... </TD></TR></TABLE>

Then how do you plug in the OBD-2 P72 ECU into your car?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94eg! &raquo;</TD></TR><TR><TD CLASS="quote">Then how do you plug in the OBD-2 P72 ECU into your car?</TD></TR></TABLE>

I extracted the pins from the male ecu plugs (obd1 plugs) of my car. Then I wired the extracted pins to the ends of the obd2 ecu plugs. I do this when I use an obd2 ecu.

I only get a knock sensor code when I use an obd1 p72 with a obd2 motor. Logically when I use an obd1 p72 ecu I shouldn't get any problems because the ecu pins are in the right place. I also added a wire to ecu plug for the knock sensor. So I should not have any wiring problems, but I do.

In order to use the obd2 p72 ecu, I need to use obd2 p72 ecu plugs. Right? Of course. Extracting pins from obd1 plugs and wiring them to OBD2 plugs opens up protential problems. But I didn't get any problems.

cliff: USDm obd1 p72 ecu with obd2 gsr = knock sensor code.
USDM and JDM obd2 p72 ecu with obd2 gsr = no knock sensor code
From what I know, all these ecu are unchipped.

 

with all this wiring work you've done, have you checked the line with a simple volt meter?
the signal should be faint (~1V pulses) but it should be there. If there is any voltage offset (constant voltage on the line) then you have a wiring problem.
the OBD2 setup may have had a bad connection (due to the pins) that looked like a signal to the OBD2 ECU so it didn't set the CEL. Good connection to the OBD1 ECU = CEL.

I'm shooting in the dark here, so don't laugh too loud at that idea.

 

Hey Relic1, I forgot to mentioned about my wiring.

First, from the KS to the strut stower the wire is partial shielded. Reason for this, the engine harness is JDM. I extended the JDM harness to use in my USDM car. Not sure if the wire is partial shielded will cause the ecu to throw a KS code. I soldered and shrank wrapped the soldered joints of the KS wire. And since most of the KS's wire (length) is not shielded, I had it in a different wire loom so it won't get any interference from diffrent wires. I might get some shield from Radioshack and rewire the KS's wire agian. Hopefully this would solve my problem.

Second, from strut tower to ecu the wire is not shielded, not that i could remembr.
From what I understand, Honda uses 18gauge wires for the engine harness. The shielded wires from Radioshack has 2 24 gauge. Do you think wiring both 2 24 gauge wire to one 18 gauge wire would make up for the size of the two 24?

Please some one help out a Honda bro out.





Modified by eh2 at 4:32 PM 5/5/2007

 

Ive used radio shack microphone wire on a few honda's knock sensor wiring with no knock code.
ground the shield to where the rest of the shields are connected, which will be at the shock towers and not at the ECU. That's how honda does it.