Ok, I did a search and didn't find the answer I was looking for.

I've got a 5.0L TBI engine that I'm using for an engine swap while using a manual tranny. Thus far, the swap is wonderful except for one wire: The "park/neutral" switch. Where the fawk is this supposed to hook up with a manual tranny so I can have the VSS work correctly?

In an automatic, this is switched based on the park/neutral of the tranny(don't recall whether it is grounded when in P/N or in drive)

I've also looked through 2 factory manuals and 2 Hayes manuals and didn't find the answer. All of them show a funky "split" for the manual tranny but it is not clear what the fawker is doing.

I'll probably kick myself a lot when I get the answer for not seeing the answer.

And before I get the answers of "just ground it" or "just tape it", this swap has to be CA smog legal and I'm dealing with an ANAL referee who wouldn't tell me what to do with the fawker other than "I don't see a VSS":mad:

TIA for any information that you can provide,
John

just put a switch on the dash then write above:
"if tranny is in park, turn ON"

hehe

i dunno i was gonna tell ya to ground it :D

If this is the wire I am thinking of It should ground when in P or N and should prevent the engine from cranking when not grounded.. You could get another brake light switch and mount it so it is activated by the clutch pedal.. hook a ground to one side of the switch and your wire to the other.. You may also want to put a spst in there also so you can bypass it when you kill the engine in a difficult situation..

Not trying to be an ass, but I just taped mine, and my VSS works fine. I am running an auto chip, with the 4500. Every works fine, and the VSS shows on the scanner.

Thanks for sharing this information guys. I too am using an auto chip with a stick (SM465) and have been wondering for months now if it will work. I planned on grounding the park/neutral switch wire too, so that I could start the vehicle in any gear. I remember how handy it was with the old 79 setup (T150), when trying to crawl out of something off camber that my engine wouldn't run at...just used the starter motor to chug my way out.

So, anyways, thanks for sharing gang.

Chris

hy_desert_4wheeler,
The wire I'm talking about is a orange/black wire and effects the VSS. It is not related to the starting circuit.. and FWIW, the starting cicruit is exclusive of the ECM needed wires.

The wire you are refering to is dark green/white.

But, yes it is grounded when the tranny is in park or neutral.

ALL:
The problem with leaving the wire free is it effects the idle of the vehicle as well as the VSS.

Can anyone tell me what a stock manual trannied TBI engine does for the P/N switch?:(

From what I recall, the manual trucks didn't have any type of park nuetral switch. It should work open, if not, then it grounded (don't recall off the top of my head which way, but I'd start by leaving it open). I run a manual chip in my auto truck; one of the benefits of the p/n switch in an auto truck is that the idle remains stable when you put it in gear, w/out it it drops a bit when going from park or nuetral into gear, then recovers.

TBI trucks (at least the '87-'89 R/V series) did NOT have any type of electrical interlock on the shifter, it is all in the mechanical linkage between the key/shifter/ignition switch. The switch at the base of the column (that contains the p/n switch) is the same as the older (carb'd) trucks; the two terminals on the switch that were used for the starter interlock on the older trucks is used for the p/n switch on the TBI trucks.

Also you can buy a cheap scanner at Checkers/Krogen for ~$150, I went years w/out one, and wish I'd bought it a lot sooner.

Pete

The P/N switch is used for idle and part throttle operation. Basically, you can setup a switch to ground the wire if you want to or run with it open. The aftermarket wiring, (i.e. Painless) just grounds it in the harness and does not tell you about it! :flipoff2: The reason why???? If the switch is open, (i.e. you are in gear) the ECM looks for a VSS signal to see how fast you are going. If it does not see any engine speed .... then you get the SES light and an error code. The ECM wants the vehicle speed so it can turn on the EGR and help you get a little better gas mileage. Also, if you are in either P / N, the idle will go down a few hundred RPM since you are not in gear.

My truck is an auto with a TBI. I have the P/N wire hooked up to a switch so I can get a reduced idle after the engine warms up.:)