1986 chevrolet g20 shift linkage - 1986 Chevrolet G20

Here is everything from 1982 - 87. The wiring and wire colors are all the same to the same sensors or components. Have fun!
https://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f80386616

hi Cabbie.
this is all i could find.go to this link and see if it helps you out.
Vacuum hose diagram for 1986 Chevrolet G20 Box truck with 350 engine...

to me, it sounds like the actual shift linkage has a problem. a snapped or loose cable can and has done that.

have the battery tested, you may have a weak cell.

We are assuming that you are talking about 1986 Chevrolet Truck G20 3/4 ton Van 5.0L 4BL OHV 8cyl...
The Fuel Filter is located under engine cover, center, upper engine area, rear of alternator, mounted in fuel line.

Hope help with this. Good luck.

it has more than one speed sensor.
there are many factors that control the shift.
start with the simple stuff
1. how is the fuild level?
2. what condition is the fluid in?
3. is the shifter linkage working correctly?
4. are all the sensors pluged in?
5. is the cooling system working correctly?
electronic failures may turn the check engine light on.

If this is automatic check you transmission fluid level. If that is good you will need to take it to a transmission shop and have it repaired. If it is standard you need to have the transmission serviced.

Clarification please... Do you mean by "go into" as the shift linkage will not move into the forward ranges or that the vehicle will not move forward? Both are possible scenarios but very different. Let me hear clarification for sending a test procedure for either one.

is it parked in a steep hill, if so,try to releave some pressure off it,and try to shift it,if not,block wheels so van wont move,inspect shift linkage,if ok,undo linkage from tranny,try shifter invan if it moves ok,if not,inspectshifter and linkange,if its ok,try moving shifter arm at tranny,be careful!if it doesnt move, youll have to take oil pan off tranny and inspect park gear lock.

is there any resistance at all when you shift gears. sounds like the linkage is broken... perhaps right at the transmission itself.... should be an easy fix as i would guess the clip holding the linkage on has failed.
other option is that the transmission has failed.

is that an automatic or standard tranny ?

Robert