I got two codes from my 87 gl SPFI d/r 4wd 5sp. with wiring harnesses in the engine bay ( which isn't were most are I understand)

 

so

 

I got the VSS vehichle Speed Sensor, what is it and would it change preformance?

 

I also got the nuetral switch code, what is that and also what is its relivance?

You're reffering to the 2 green test connectors under the hood? That's were they are on the SPFI models. MPFI and old carbed are under the dash. anyway, to answer you're questions

 

VSS is located in the dash, part of the speedometer assembly. It could be that it is not sending signal to the ECU, or it could be an intermittent problem. It's not a critical item and won"t throw the code in U-check or Light the ECS light.

 

Neutral switch code could be being set by the Neutral switch itself(side of tranny), or by the Clutch switch(Clutch in is seen like neutral). Again not terribly critical. Could affect some driving/idling issues, but most likely not a big deal. You could check those circuits to makesure the switches work and are not shorted. It may be a connection issue where a momentary bad connection throws the code.

you may see these codes when the car is not running. the vss will relate to the speedometer.

does your speedo work? If not, that's the cause of the VSS code. Most likely a broken speedometer cable.

 

I can't remember off hand what the neutral safety switch is for. Some searches should tell you what you want to know.

 

-Dave