Speedometer sensor wiring

I'm trying to troubleshoot why speedo isn't working and have a couple questions:

-the sensor seems tied into the brake malfunction warning/wiring. I've removed the sensors from each brake, so the that wiring isn't functional anymore- now I'm wondering if I need it in order to have the speedo operate/receive the signal from the speedometer sensor? Or can I just ignore it?

-where does the wiring for the speedometer sensor end up in the engine bay? Fuse box? 14 pin connector? Passenger foot well? It seems to go straight up into the body above the transaxle-

-was just gonna clean/test and replace if necessary, but now I'm wondering about the wiring-

Thanks for the help-

What year and model car do you have?

87 944 NA

I don't know of the speedo circuit surfacing at any of those connectors. Without carpet in my car, I can see that the wires go up through the floor, over to the driver's side behind the rear seats and then into the big wire bundle that goes forward under the driver's door sill.

Rich

The speedo gets it's signal from the sensor on the trans. It doesn't go through any of the brake sensor wiring. If you cut out all the brake wiring, you may have inadvertently cut the speedo wiring at the body.

Yeah I see now that it just shares a clip w/ the brake sensor- it isn't wired into it.

What I'm more worried about is that I cut it off in the engine bay, but thanks Rich- I will see if I can locate on drivers side sill

I'm 90% sure it doesn't go in the engine bay at all. Should only be inside the car from the rear seat forward.
Did the speedo work before beginning the conversion? Is this the same trans that was already in the car? I've replaced a lot of bad senders on the trans.

Sorry to Hijack your thread... But I have a quick question while we are on the subject.

Since my swap is going into an 83' and my speedo works off the front spindle, will I just install the the VSS sensor on my AOR Transaxle, and tie that into the GM ECU? Or is more efficient to eliminate the spindle reading, and adapt the gauge to read a signal off the VSS?

Thanks!

the gm computer cant read the signal from the porsche sensor, they are 2 different types of signals. you will still need the aftermarket sensor kit for the gm computer. the factory speed sensor is just along for the ride.

your early speedometer is cable driven, there is no way to hook a speed sensor to it as its all mechanical. no reason to change this, unless your going to change the front spindles. the spindle with the speedo cable is a weak point in the front end of these cars, its recommended to change it if you plan on doing any hard driving. there are a couple option for the speed o in that case, you could have a speedo cable made to drive off the transmission where the speed sensor screws on, or you could run a converter box that will drive a mechanical speedo off an electronic signal.

Thanks Sharkey! - That was my general consensus as well.

I will most likely buy a dye penetrant crack testing kit, to baseline my current spindles and go from there. I don't see anything more than spirited driving being done in this car. Although I will be running 10" wide wheels in the front, so that might add extra force...

from what ive read, with that much tire, id be changing the spindles

sharkey wrote:from what ive read, with that much tire, id be changing the spindles

Ugh, okay so let me ask a few more questions. Did some quick reading/searching and determined that the 87' Spindle seems to be the most durable. I would obviously mate that with the 87' hub and 87' rotors. I have the Wilwood 4 piston calipers that can fit on any 944, so no problem there.

Can I maintain my early offset for wheel fitment? I have some custom wheels being made that are based off the early offset...

Also, will these spindles attach directly to the early steel control arms? I'm assuming the tie rod ends might be different. And I see that there would be some modification done to the strut assembly to get the early to fit as well.

This has turned into a nightmare! The issue is I have the Spec 1 suspension kit from Paragon, so I am trying to retain as much as I can.

*** EDIT *** Moved conversation into suspension mod section for better visibility.

Hotrodz of Dallas wrote:I'm 90% sure it doesn't go in the engine bay at all. Should only be inside the car from the rear seat forward.
Did the speedo work before beginning the conversion? Is this the same trans that was already in the car? I've replaced a lot of bad senders on the trans.

I'm not sure if it worked before- the car had a bad motor/never ran.
Yes, same transaxle that came w/car.
I'll replace the sensor and see if that works- seems like the bearings in it have a lot of wobble.

I'm also having problems with the tach- I did the whole pcm pin 10 to the #2 wire on the 8 pin connector
thing without results.

Lt1 swap recommends (for 2003+ GM PCM's) to install a resistor and 12v fused power to the #10 wire.
Anyone done that with good results?
Here is his recommendation:
http://lt1swap.com/lsx_tach.htm

Jasonscottw wrote:

Hotrodz of Dallas wrote:I'm 90% sure it doesn't go in the engine bay at all. Should only be inside the car from the rear seat forward.
Did the speedo work before beginning the conversion? Is this the same trans that was already in the car? I've replaced a lot of bad senders on the trans.

I'm not sure if it worked before- the car had a bad motor/never ran.
Yes, same transaxle that came w/car.
I'll replace the sensor and see if that works- seems like the bearings in it have a lot of wobble.

I'm also having problems with the tach- I did the whole pcm pin 10 to the #2 wire on the 8 pin connector
thing without results.

Lt1 swap recommends (for 2003+ GM PCM's) to install a resistor and 12v fused power to the #10 wire.
Anyone done that with good results?
Here is his recommendation:
http://lt1swap.com/lsx_tach.htm

I had to install a pull up resistor in the last car I built. It depends on what year GM ecu you use. Some early ecu's have enough voltage to run the tach, while the later ones don't.