86 in dash vss

[jameslleary]

Ok...here goes. I have done plenty o swaps in the past, where clients have had everything ready to install....and i have been through quite a few harnesses, thats why my questions seem newbish.
this is a new one for me, because I have always had inline vss's to work with.
Is there any way to test the speedometer cluster mounted VSS in my 86 burb to see if its working, and, can i use it to provide the required signal to my 7747?
Money is funny as of late....started this swap when i was employed, but need to finish it up. all i have is the 4 pole ac vss that was on my tpi setup.
thanks guys!

[1project2many]

You can test the sensor by spinning the cable or speedo head and measuring the voltage out. Speed sensor is connected to ign and gnd and has signal out wire. Find 86 or 87 truck FSM with diagrams and it will show sensor connections. Speedometer signal out wire connects to ecm directly at B10. Wiring diagram on this site is for later vehicle with magnetic sensor and speed signal buffer.

[jameslleary]

ok. thanks. some more info here. I DO have the signal wire(yellow, from the vss box)that went to the old cruise module, hooked up to the brown wire at b10. i have driven the truck a few miles, and i do not get a ses light comming on, would that also mean its working, or does the 7747 throw a code for vss?I know, I should know this, but in my world, the dumbest question, is the one that you dont ask.
Jim

[EagleMark]

First we have never discouraged newb questions, that has brought about detailed conversations about a certain topic/sensor/circuit that we have all learned from.

7747 will set a code if no VSS is detected, I have veiwed them with scan tool. But I do not remember if it will cause check engine light to come on. HTH!

So did you get CEL before? Usually if you fix the issue or the issue is intermetent the light will go off, but the error code will still be stored and seen on scantool for a certain amount of time, I think it's set to how many startups without the code reocurring on 7747.

[jameslleary]

I have only driven with it hooked up. i do get the cel when i disconnect the spout to set the timing. my trans is not locking up, but i think that i may have hooked the brake switch wire up to the wrong side of the resistor that is inline in the harness. i still have to yank the harness back out to clean it all up, and i need to go find a piece of sheetmetal to make a patch for my throttle cable hole in my firewall, as i had to make it a bigger rectangle for the camaro tpi cable, instead of the small square hole for the truck cable.
Edit:I may want to talk to you about the tune you are running in your Suburban at some point.

[EagleMark]

IIRC the brake switch has to give power all the time and turn off when brake applied to release TCC. Don't remember a resister?

Not much special in my suburban tune, stock motor, used Dave W spark table, did the HiWay lean cruise trick started by RBob years ago, then did WOT with wide band O2 sensor. Changed torque converter lockup to 40 MPH instead of 35 MPH because so many streets near my house are 35MPH and radared regular. So to go 35MPH was impossible, you could go below and stay out of lockup or when it locked up you would be above speed limit, rinse repeat, rinse repeat.. was a pain...

[jameslleary]

IIRC the brake switch has to give power all the time and turn off when brake applied to release TCC. Don't remember a resister?

Not much special in my suburban tune, stock motor, used Dave W spark table, did the HiWay lean cruise trick started by RBob years ago, then did WOT with wide band O2 sensor. Changed torque converter lockup to 40 MPH instead of 35 MPH because so many streets near my house are 35MPH and radared regular. So to go 35MPH was impossible, you could go below and stay out of lockup or when it locked up you would be above speed limit, rinse repeat, rinse repeat.. was a pain...

have you had any issues with detonation? you and i pretty much have the same truck, except i have a K and yours is an R.