87 ranger will only run with diagnostic connector grounded

[junkyardjeff]

It is looking like there might be a problem with the ECM or is there anything else to look at before getting another ECM.

[wayne petty]

could need a PCM..

disconnect the SPROUT timing connector and see if the truck will run.. that is the odd plug shaped like a fuel injector connector.  

got a wiring diagram...

can you do a power test..

probe end of a test light into the coil positive connection.  ground the clip..  slowly turn the key on and crank the engine.. do you get light ON in Run, Cranking and Run..  that tests the ignition switch output..

move the probe to the red wire to the idle air control motor..  do the same ignition switch movement.. again should have power in Run, Cranking and Run.. this tests the EECIV main relay output..

i usually do a similar test at the inertia switch.. i run it twice..  one on each wire..  but it should have power for 2 seconds at key ON.. then again while cranking.. then shuts off after 2 seconds when you have stopped cranking..  this checks the fuel pump relay output..

if you can get the truck to run.. perform the voltage drop test..  it only takes a few minutes.. http://i.imgur.com/WMDprhm.jpg  

next to the ECM is a pair of ground wires.. please make sure that those are cleaned on both side of each ring terminal with a wire brush..
the later rangers have the computer thru the top of the firewall..  this is the proper wiring connection for the grounds.. a pair of wires out of the harness and a ground strap that comes from the engine.. the double sided green stud  then the plastic harness support bracket under the top nut on the stud..
http://i.imgur.com/KfqJA7I.jpg


you might want to check the solder joints on the circuit board ..

http://i.imgur.com/U3JoxbK.jpg

you can usually get a good idea of what part number you need from this site..

https://www.cardone.com/find-parts  i usually don't give up the exact ecm or PCM till the car/truck is fixed and has been test driven..


since you can get it to run with the diagnostic connector jumpered..please perform the KOEO and KOER tests..

the trouble shooting info is here..

http://oldfuelinjection.packrad.net/

post what you get..