hello, 

i have 1989 with the 2.5 

to set the timing ,

1) mark the crank pulley with chalk ( so you can see it under the timing light )

2) get the motor at operating temp. 

3) under you dash theirs a aldl port  you want to get a jumper wirier an go from "a" port to "b" port.

4) loosen the distributor clamp hold down ( not to loose, don't want it flopping around) 

5) start the truck (make sure your still at operation temp (if not let it warm up) once at temp use you timing light an move the distributor  till you get 8 degs of timing.

6) re-tighten your distributor. once tight recheck your work making sure your still an 8 degs of timing with truck at temp. if not go back to step 4 

7) shut truck off, pull the jumper wirier  from aldl port. 

8) disconnect neg. battery cable for 30 seconds ( re-install battery cable) 

make sure that the key is in the off position when removing battery cable to prevent damage to the ecm   

an you good to go  hope this helps 

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