Jeep 401, 16197427, $OE, what do I do about a knock sensor? Getting code 43

[rang-a-stang]

My rig is up and running but I am getting a code 43. I currently have 5V jumpered to the knock sensor input (I think B15) when the computer is on but as I read how the computer tests the knock sensor circuit to trip a code 43, I will always fail the test and trip that code. Should I disable the flag? Is there something else I should do?

for clarity, I am a total newb so feel free to basic on me. Using Tunerpro RT to tune.

[1project2many]

Did I miss the reason why you aren't using a knock sensor?

You can deselct the code 43 flag to prevent the code completely but I'm not sure what side effects this creates. The older C3's would inhibit other functions if code could not determine the ks was present and working.

[dave w]

There is the option to actually connect a knock sensor to the 19197427 computer. Instead of screwing the knock sensor into the block (where it is supposed to be). drill and tap a hole in the Jeep frame for the knock sensor to screw into. Once the knock sensor is securely mounted in the frame, connect the knock sensor wiring to the knock sensor. With the knock sensor mounted in the frame, code 43 will be PERMANENTLY disabled. Not all knock sensors are same, you will need a knock sensor for $OE. Having a knock sensor mounted in the frame, only disables Code 43. A knock sensor mounted in the frame will not protect an engine that is KNOCKING. No chip programming modifications required with a frame mounted knock sensor.:cool:

dave w

[rang-a-stang]

Did I miss the reason why you aren't using a knock sensor?

You can deselct the code 43 flag to prevent the code completely but I'm not sure what side effects this creates. The older C3's would inhibit other functions if code could not determine the ks was present and working.
I'm not running one because I had read somewhere that a bad KS signal is worse than no KS signal. I will not be offended if you tell me I am wrong or that is a ridiculous idea. :scare:

Since AMC never had a KS in their V8s, I didn't think there would be a good KS to install. You're thinking the same thing I am about just disabling the flag (not sure what side effects this creates).

There is the option to actually connect a knock sensor to the 19197427 computer. Instead of screwing the knock sensor into the block (where it is supposed to be). drill and tap a hole in the Jeep frame for the knock sensor to screw into. Once the knock sensor is securely mounted in the frame, connect the knock sensor wiring to the knock sensor. With the knock sensor mounted in the frame, code 43 will be PERMANENTLY disabled. Not all knock sensors are same, you will need a knock sensor for $OE. Having a knock sensor mounted in the frame, only disables Code 43. A knock sensor mounted in the frame will not protect an engine that is KNOCKING. No chip programming modifications required with a frame mounted knock sensor.:cool:


dave w
That's a good idea! Maybe I will grab one and mount it in my cab just because my KS wire was clipped about a foot from my computer and I do not want to have to run another wire through my firewall grommet (it's super tight already). Copy that (will not protect an engine that is KNOCKING). I am still running the stock timing tables and will be keenly aware to listen for knock.

Are $OE and $OD KSs the same? I am thinking of transitioning over to $OD...

[1project2many]

I'm not running one because I had read somewhere that a bad KS signal is worse than no KS signal.
Well, yes and no. You'll usually be able to pick out the difference between real knock and false knock when reviewing datalogs.


Since AMC never had a KS in their V8s, I didn't think there would be a good KS to install.

Find a sensor from an engine with a similar bore and you'll be ok.

[dave w]

According to Standard Motor Products (1994 / C2500), both the 5.7 liter and 7.4 liter use the same part number Knock Sensor **KS6**.

The threads of the knock sensor need to be GROUNDED.

dave w

[rang-a-stang]

okie dokie! There is one in stock at my local McParts. I'll pick it up either tonight or tomorrow. I have the connector handy in my parts pile. I will make a small bracket for it with a solid ground and mount it in a position where it won't get bumped or feel false knocks. Maybe sometime down the road, I'll try plugging it into the side of my block and see if I can get it to work correctly as it was designed, but for now, I am going to keep it in the cab. I really appreciate you guys hooking me up with this info!

[rang-a-stang]

Last night I picked up a Knock sensor (Duralast SU154 for a 1995 C3500, 7.4L), made a nifty bracket for it, threaded it in, grounded the bracket, soldered the connector onto the wire, and fired it up. Got a code 43 again.

I measure continuity between the KS connector center pin to PinB15 on my harness and got 0 Ohms. I measured continuity between the KS body and body ground and got 0 Ohms.

Did I get the wrong sensor? The sensor is position about as if it was threaded into my chassis, should I position it differently? Is there a test I can do on the KS (maybe I got one that was bad, right out of the box)? this circuit seems so basic, not sure why I am having trouble with it...

[dave w]

Measuring from the center of the knock sensor, were the wire plugs in, to the treads the resistance should be very close to 4000 (4K) ohms.

dave w

[rang-a-stang]

This knock sensor has 1000 ohms across it. Looking for another one (the correct one).

[rang-a-stang]

Went back to McParts and traded Knock sensors. I brought my Multi meter with me and measured it. Got one that is 4K ohms. I got home, plugged it in, and Voila! It worked, no more code 43!

[1project2many]

Good news. Yet another example of "New does not equal good."

[tayto]

i reckon if you bought an ac delco or delphi sensor there would have been no issue. why not install the knock sensor in the block? if it's too sensitive i've heard of some folks installing a brass 90* fitting then the knock sensor.

[rang-a-stang]

I think the difference in the 2 I had was one was for an Auto and one was for Manual. I don't know which sensor is which (meaning which sensor goes to stick and which goes to auto) which is why I brought my multi meter. wow, that sentence had a lot of which'es in it...

I hope to install the sensor in the block at some point. The original write up I read on how to add TBI to my rig said to just put 5v on the knock sensor pin so that's what I did. At this point I am just trying to get my truck to run correctly. Once I have it running a bit better I will experiment with adding it to my block.