I have a 90 Si rex with a JDM b16a swap. I have a CEL for VSS and Knock Sensor. The VSS code I'm guessing is due to the speedo cable being broken, but I'm not too worried about that and will get to that later...


As for the knock sensor, here is my problem: The engine harness is a nightmare. Originally the wire/plug for the knock sensor was floating around the engine bay somewhere, but now that I've finally spent the money on a replacement sensor, I can't find it. Not to mention that there is another plug on my engine that I cannot find the wire for either. Looks like maybe the thermostat? Plug is right next to send hose from radiator. Pic of that shown below:





I do not plan to stay N/A and hope to be boosted by April. The car is NOT my DD and I have some time to toy around with it and not worry about downtime.


My question is, should I invest in another obd0 b16a engine harness, or go with an obd1 harness, change the dizzy, etc., and get an obd1 ECU (with hondata if I can find it!) due to the fact that I plan on boosting in the immediate future? With this knock sensor CEL, I cannot pass emissions and get my tag. (Once again not a big deal due to non-dd status, but being that I'm already 6 months paid ahead on my insurance, I'd like to at least drive it for fun some days...)



TLDR: What do you all think? Replace the obd0 harness, or rewire it for obd1?

Thanks for any input and advice!

 

Knock sensor is easy. There should be the knock sensor on the back of the B16 block. It will take the standard 2 wire plug that honda uses and only use the top wire I believe. The knock sensor is a single wire that runs to B19 on the ECU.

That's for the fans. Some B16s have the fan switch on the back of the block. Do your fans even turn on? If not you need to run the plug to that point there.

Use the motor harness you have. If you convert to OBD1, it is very easy to do the wiring. Heck, I did a write up on it.

https://honda-tech.com/forums/honda-crx-ef-civic-1988-1991-3/how-obd0-obd1-3175858/

Go ahead and bump that thread because everyone is confused on what goes into the conversion. It is very easy.

I explained how to hook it up, it's very VERY easy.

Keep the OBD0 harness and wire it for OBD1 following my Write-Up. Also, the ELD is wired to B19 on the stock wiring. The OBD0 VTEC ECU uses B19 for the knock sensor. Therefore you shouldn't wire in the knock sensor if you plan on going to OBD1 since a lot of the OBD1 ECUs do not have a knock board.

 

I know where the sensor is. I just cannot find the wire in the harness that runs to the ecu. Previous owner let it float around the engine bay, and I think it might have been ripped out at some point while I was driving. Is there a way to wire it straight to the ECU without using the harness plug? Maybe with just some standard wire and slide it through the firewall and pin it in? That is why I was considering a new harness, to avoid that headache.




Also, what fans are you speaking of? Radiator? vent fans? I believe both turn on but I'm on my way downstairs to check for certain. It does not overheat though.



And since you seem extremely knowledgeable, do you think my VSS code is due to a faulty speedo cable, or the sensor itself? Tranny is a gsr YS1.


Thanks for the help!

 

Upon further inspection, my vent fans come on, but my radiator fan does not. (At least not while Idling, I didnt take it out for a spin, just turned it on and heated it up.) But my radiator IS plugged into the harness, as seen in picture:

 

Exactly as I thought. Okay. I have the fix for you. Follow the wiring from the fan plug. It should lead you to a plug that might be on the back of the block. On the stock D-series motor the fan switch is located on the back of the motor block. However, on the B16A that you have it is located on the thermostat housing. You will have to get a plug that fits the thermostat housing on your motor. Then unplug the wires from the back of the block and extend them to go to your knew plug on the thermostat housing.

Here is an easy test to see if a plug is for the radiator fans. It should have 2 wires going to the plug. Take a piece of spare wire, strip it so there is exposed wire on both side of it, and plug it into the plug. This is basically connected the 2 wires in the plug together. This is known as jumping the switch. If the plug is for the radiator fans, they should come on. If it isn't for the radiator fans, it may blow a fuse in the worst case scenario.

This is probably a little confusing without pictures. But I'll try to explain it more if you need more help.

 

Trust me, you are the FARTHEST thing from annoying! I've owned this car since april and noone has been able to be this helpful since then. And you are correct, I got this car in a trade and the swap was already in it. It has been a wiring nightmare ever since, and the first day I got it the starter blew due to problems with an aftermarket alarm system... But thats a story for another day.

But I popped the hood once again and here is what I found:

Traced the loom back from the radiator, and thought I had found the plug you had mentioned. It fits the plug on the thermostat. Plugged it in and turned the car on... Still no fan spin. So I went back under the hood, and saw that the wire actually comes from inside the firewall, not the loom. It is also a single black wire, not 2 wires. This plug ALSO fits my replacement knock sensor, which leads me to believe that is what it goes to. I also forgot to mention that I believe this wire was originally plugged into this very janky concoction that is zip tied to the fuel rail. If I remember correctly, this was used to trick the ECU into thinking the knock sensor was there, and hence pass emissions. I think he called it a transducer? Might be completely wrong though.. Here is a pic of both the plug, and the fuel rail:





And here is a picture of the top of the differential where the cable enters. I do still have the black rubber grommet that went around the end of the cable and onto the VSS, but it was not working before I removed that to inspect the cable. I've been told that there is some kind of metal clip that keeps the cable in, but that was not there, and the Speedo and VSS worked for many months without it.

Thanks again for the help. Now that I have a dependable DD I'm trying to take care of all of these problems that I let slip for a while.

 

Also, if this will help at all, here is a picture of my pr3 ECU. It appears that some sort of 'jumper' is used, as seen in the bottom left. That black loom is just lengthy and is all one piece, not two separate pieces running towards the bottom left.

 

After tinkering a little more with the car today (its been my one day off in a long time...) I have tried a few things:

Pulled cable out of tranny and hooked up to electric drill and had GF watch the gauge. The speedo gauge DID register speed when I spun the drill.

I then made sure cable was COMPLETELY pushed into the tranny, until it clicked. I then taped the cable down to make sure it wouldnt come out. (TEMPORARY measure so that I could test if it worked without it popping out). Then drove around a bit, but speedo did not register any speed.

Is the gear-driven VSS in the YS1 Transmission broken? Is there a good way to pull it out and check for sure? Is there an easier/cheaper way to purchase a replacement without going through an acura dealership?

Sorry again for all the questions. Just trying to get this thing running tip top by tomorrow. Will probably make another thread in a transmission section just for this issue. Thanks!

 

From the way you described how you put the cable back into the trans, it seems like you are missing a part.
There is a little wire clip that holds the cable in place. Without that, the cable likes to pop out and there is no positive way to tell if it's all the way in.




Here's the gear assembly with a cable inserted and the clip in place.
Once fully assembled, the clip won't allow you to pull the cable out.
Make sure everything is in place and pull on the cable to ensure that you are unable to pull it out.



If you had the clip and it still doesn't work, then you can pull the gear assembly out.
Then you can spin the gear on it and see what's going on.


Remove the one bolt holding the gear to the transmission.
This will release a small locking plate that slides into the side of the gear assembly.

Grab the base (closest to the trans case) of the gear assembly with large pliers and twist while pulling.
Don't squeeze on the tube for the cable or you will likely crush or bend it.



Looks like this when finally removed

 

As far as your connectors go, Honda uses the same 2 wire connector for a lot of things. The IAT sensor, knock sensor, IACV, ect ect all run on the same plug. So just because it fits doesn't mean it's the right place.

I want to say there are a lot of ways to trick the ECU into now throwing the knock sensor code.

The thermostat will only turn the fans on when the car is hot enough. Take that plug that you plugged in, unplug it. Find a wire and connect one side of the plug to the other side. You should see the fans come on if it is the fan switch.

 

I changed out the Knock Sensor and got CEL 23 to go off. I had to RE PIN the connector (it was in b18, not b19). Unfortunately, I still have CEL 17, and the speedo is still not working. I'm going to look for a replacement for the gear driven mechanism that 4drEF posted pictures of, as I have already made sure everything else is working fine. Hopefully it will come with a replacement c-clip.

I just want this thing street legal damnit!

 

Yeah. You shouldnt have many issues with finding the gear driven portion.

 

I have a sensor missing a pin, but the gear part is there..PM me if interested.

 

When I swapped my b16a into my crx, I had a hell of a time with my speedo cable. (It's fine now) it looked and felt like it was in the vss completely, but it truly wasn't. (I didn't and still don't have the little clip for it) I just pushed until it wouldn't go in any farther.