ToniJ1960

Does anyone know where the wires from the vss run to? I want to know the full routing from the connector at the transmission up to the dash connector.

Where can I tap the vss wire at to connect my new gps sender?

nobodycls

The wires go into the main harness across the back of the motor and into the firewall on the passenger side behind the valve cover. Inside the car above the kick panel, that wiring harness connects to the ecm, and coming out of that harness there are connectors that connect the underhood harness to the dash harness, and that would probably be the easiest place to tie into the vss wires. There is a double row connector with 15 wires, and a single row connector with 8 wires - that is the one you want. The wire colors are tan/white and pink/black, and are in connector terminals D and C, respectively. You should be able to pull down the connector once you find it, and be able to work on it without too much trouble. I pulled the knee bolster out on mine, but I think you can still get at it with it still in.

ToniJ1960

So I guess right at the dash connector? I had it out once I can get it out. Or is there somewhere like behind the radio I can get to it. I think thats where Im going to install the gps sender. Do I send the signal to pink or black wire? Or tan or white? The 84 has the vss go to the dash and from the dash to the ecm I thought.

Cliff Harris

The connector is below the ECM. C237.

Pink/black is 12 volts when the ignition is on, so that's not the correct wire.

The purple wire goes through C237 pin C. This wire is connected to ground inside the instrument cluster.

The tan/white wire on C237 pin K changes color and is yellow on the instrument cluster side.

These are the wire colors on my '86. It's possible these wires changed colors over the years, but my experience is that GM is very consistent with their wire colors and circuit numbering system.

nobodycls

Edit - My 84 factory manual shows the the same color wire on both sides, but the pink/black wire changes to purple, and the tan/white changes to yellow, but they are indeed on pins C and D - a visual check will confirm.( pink/black means pink with a black stripe) In 86 all the wires for the same functions are in different locations, and even on different connectors. I know this because I just got done adapting an 86 harness to plug in to my 84 harness. You could put the gps unit behind the radio and poke the wires out to the pass side to the connector by the ecm. The only other place to get access to the wires is at the cluster connector. Does the gps unit have a seperate antenna? make sre it has a clear view of the sky. An excellent place to put it is just below the dash pad above the radio and a/c controls, vents. Once you get the dash pad out, there is a perfect spot to lay the unit/antenna on top of the vents with plenty of room and a clear view of the sky. My car had a gps tracker installed in this location.

ToniJ1960

I was thinking of attaching the sender and antenna to the bottom of the dash pad can you tell me how to get it out or off?

ToniJ1960

And so, if I connect there I use the tan/white wire if I connect at the dash I use a yellow wire. I might tap in at the dash connector and verify everything at Batee. I dont even know if my cluster works yet until I hook this sender up. Im getting anxious but its freezing outside snow on the ground and I dont want to screw up either.

nobodycls

Best thing to do at this point is use a meter to verify continuity from the vss sender plug or the connector by the ecm to the proper pins on the cluster connector. I bet using your electronics background you could build your own signal generator to test the mph display on the cluster. Batee has all the info you need to hook up ground and power and other inputs to test the parts of the cluster. I tested my spare parts cluster this way.

nobodycls

I plugged the 84 connector from the underhood harness back into the dash harness connector to take a pic

http://s790.photobucket.com/user/***...F0737.jpg.html

The top part is the dash side, and the vss wires are the 3rd and 4th from the right. The first and second wires are the 12 volt power to the injectors. (the melted spot is from the underdash bulb laying on the connector, like that when I got it)

nobodycls

There are two screws in the defroster outlet, and several across the bottom of the pad across the whole instrument panel all the way to the pass side door. There are also some clips at the front bottom side of the pad that slide into slots below the windshield, so you may feel some resistance until they slide out.

EDIT - The P.O. had torn a large chunk off of the pad by removing it previously, but it looks like you can pull the pass. side back after pulling the pad straight back a couple of inches first, and get clear of the steering wheel by removing it out the pass side with the door open, but it is hard to tell for sure with the chunk missing on the drivers side on mine.

ToniJ1960

After the screws come out slide the dash pad straight back towards the rear?

Im wondering what you know of my electronics background maybe you read another thread? For the record I have almost 40 years of experience in electronics, at 16 I nearly passed the second class fcc commercial license, and worked in a few repair shops on communication equipment and high end audio equipment. My early exposure was through hobby experience, my father worked at McDonnel Douglas, as a teacher at a tech school (Missouri Tech, he was friends with some well known person who worked for KPLR).

I went to community college in 1981 and studied EET for a while. I still like to fabricate pc boards, and build things I design.

If anyone ever wants to discuss anything related feel free to pm me.I appreciate all the help I get here, and Im trying to learn about this car and Corvettes as theye been a passion of mine since before I ever owned my first car.

Hopefully I will be able to help someone too sometime.

ToniJ1960

Im wondering if, since the connector is off the vss, I can pull the wires up from inside the engine compartment, snip off the connector (leaving some wire in case it needs to be reattached later,or can be) and pull the wires up inside to attach my sender? Is there any strain relief or anything holding the wire between under the car and the firewall?

nobodycls

Here is the routing of the vss wires
http://s790.photobucket.com/user/***...route.jpg.html

nobodycls

You need to pull it straight back a little to get the clips undone and be able to turn it sideways a little, then I think you can pull the passenger side back while maneuvering the drivers side so as not to hang on anything, then pull the dash pad out the pass side. I think you will have to have both doors open to do this. Mine is missing a piece on the drivers side, which makes it easier to remove, so I'm not 100% certain you can do it that way, but I think it will work. I need to pull the pad out of my parts car and see how it goes.

I read another post to see what all you had done with the vss so I could reply with something as helpful as possible, and could tell by some of your comments that you had much more electronics experience than me, lol. If it really is that hard to find a vss and gears, I hope mine never breaks!

ToniJ1960

I dont know for sure if its that hard, I made contact with a few people parting out 84s but for some reason they stopped responding maybe lack of interest in selling. In my particular case, the old vss is damaged and sealed with some paste or whatever he used. And who knows if the driving gear is even in there. This car wasnt maintained and sat a long time too. It just wasnt cared for for a long long time from what I can tell.

So, the gps sender seemed like a intriguing option and I wont have to dig into all else that could be wrong. Plus, if I ever change the rear gears or tire sizes it will still read the correct speed. I dont mind supporting some new technology myself. And, if they find their way into more cars, more of the older vss`s could end up being available and they could be less scarce for others who want them.

From that picture it looks like just the wire loom is clamped maybe I can pull out the vss wires from under the car. Wheres a good place to bring wires through the firewall?

nobodycls

If you look around on the firewall on the driver's side, there is a good chance someone has already made a hole, like on mine -
http://s790.photobucket.com/user/***...F0738.jpg.html

If there is not already a hole, that spot is a good one, it's pretty easy to get at from the inside and the outside, and with a grommet would not look bad. The P.O. ran wires through the hole on mine in an attempt to wire up the cooling fan, and almost caught the car on fire. I removed almost 3 foot of wire with all of the insulation melted off, and the foam insulation on the hush panel had a huge black burned line in it from the wire.

Funny story - I had actually worked on the car I have now about 12 years ago when it belonged to a friend of my boss at the time. They brought it in complaining that it would continue to run after turning off the key. When I checked it out, you could turn off the key with it running and it would run normally for a few seconds, then start running progressively worse until it would finally die after maybe 20 - 30 seconds or so. What I found is that they had the fan powered directly by the power wire to the HEI distributor, and since a rotating dc motor will produce a voltage, the car would continue to run until the fan motor quit spinning. I got a good laugh out of that.

Mentioning that - If you have problems with the cooling fan on your 84, the fan relay is not controlled by the ecm. There is only a temp switch in the pass. side head and the pressure switch in the back of the a/c comp. that sends the ground signal the relay needs to engage the fan. I felt the need to mention that since I see so many people that have problems with the fan on 84's

ToniJ1960

When I picked this car up in Michigan, the guy I bought it from had wired a switch to turn the fan on because he said it wasnt turning on. I asked before I got there if the switch was rated for enough current of course he said it was. That switch fell apart but I had a 20 amp one I took with me just in case. Even it gets a little warm. Eventually I guess ill check the switch in the head and the relay. For now I can use the switch I put in. But youre right a lot of people dont realize how much current the fans take and the consequence of using components (switch or wire) not up to the actual task.

nobodycls

I used a switch, too, but I ran it to a standard 40 amp relay. Someone had completely cut out and removed the factory relay and tucked the wires into the harness. I ran a wire from the battery through a 30 amp fuse to terminal 30, the wire from the fan to 87, 12v ignition on to 86, and ran a wire from a ground through a dash mounted switch to terminal 85. Then when I did the tpi swap, all I had to do was hook the wire from terminal 85 to the ecm.

ToniJ1960

Batee site says to test the speedometer, connect the - terminal of a signal generator to c11 and the + to d15. On the wiring diagram it shows d15, use for vss input and c11 for ground. C11 says, use for vss input and d15 for ground. Their hand drawn schematic isnt ready to look at.

What Im trying to determine, is if I can ground c11 and send a signal referenced to ground to d15. Or, even the other way around. In other words can I ground either d15 or c11, will either one be ok to ground. I got the vss wires of my sender plug and brought them into the car now but I cant tell whats what theyre both in black rubber. I dont see yellow or purple.So if it doesnt matter I can just ground one and connect the other to my gps sender. Im afraid of trying it until Im sure what Im doing.

So close

MrWillys

Maybe this will help:

http://www.chevythunder.com/fuel%20i...ts.htm#1986-89 pinouts (ecm #1227165)

http://www.chevythunder.com/198689_f...dy_1227165.htm