replacing a bad wire in the ecu - how?

[Ken57]

I was getting error code 34 - knock sensor. I removed the ecu harness from the ecu and removed the knock sensor sub harness (I also removed the knock sensor, it's easier to remove/reinstall the knock sensor with the sub harness connected to it.

So I tested for continunity on terminal #27 and the sub harness. Nothing. The I removed the sub harness and tested directly to the connector and terminal #27 still nothing. After cleaning the connector and still no continunity I snipped the wire from the connector and still nothing.


I realized I had a short between the connector and the ecu. I finally snipped the #27 wire about 6 inches from the ecu and presto, continunity. So it looks like the wire going into the ecu was not making a connection to the terminal. So my question is, is there a way to replace that wire? Does it just pull out?

Thanks

[moso]

you can either take the harness out (not hard at all) and replace the wire by splitting the looming and running a new one, or you can just run a loose wire out to the sensor from the ecu. you will have to take the blower motor out to get to the harness (and the ac condenser i believe) the old one probably wont just pull out because its taped in place. you may want to take out the harness just to look it over for other shorts.

[Ken57]

I was wrong about the continunity. I tested the snipped wire coming out of the ecu harness to the corresponding terminal #27 and there is continunity every time. So that tells me I snipped the wire for nothing.

The strangew thing is this, the other snipped end that goes to the connector, I checked for continunity and it worked several times and then it didn't work. So there must be a short somewhere in the wire harness? I think I might take up your suggestion of simply running a wire along the existing harness back to the ecu and connecting it to where I snipped it.

I would really like to replace my entire efi harness as it is about 20 years old and all the connectors are crumbling.

[moso]

you can have a new one for about 350 or a nice used one for around 100 depending on where you buy it ( classifieds, ebay) but the cheapest way to get a nicer harness is definitely the junkyard. i must say that my stock 92 wiring harness is in very good shape, so look around.

[Ken57]

Thanks moso for the good advice,

Well I slapped everything back together and put the new knock sensor ($133 and that included my discount! OUCH!) in and reconnected the wire I snipped. I also replaced both male/female connectors where the main knock sensor connector connects to the sub harness because both connector ends were all broken.

I also cleared the ecu and took a test drive and I'll be dammed, no error code when I checked the ecu, only the 55. I couldn't believe it so I went on a longer drive and still good - 55. So the $133 investment paid off.

But I'm still confused (but very happy) as to why the 34 code dissapeared. Maybe I didn't have a good connection when testing? But I doubt it. I checked and rechecked the continunity between terminal 27 and the knock sensor wire several times and at best it was hit and miss. So I figured the 34 code would return. Cause I sure know how to use a multi meter.

I'll recheck the ecu in a week and see if everything good then I'll just chalk this one up to weird and move on.

Thanks again
Cheers

[Ken57]

I am having the error code 34 again. I looked at the wiring schmatic for the knock sensor. It looks like the F36 black ground wire connects to the white terminal wire at some point in the harness? The white wire that connects to the ecu #27 is outlined by dashes. I don't know what that means. So if I wanted to run a direct wire from the ecu to the knock sensor's white wire, what would I do with the black wire? Run it to direct ground?

Thanks