Yo guys
Just installed an 87 motor in the 1990 blue #12, got a no start…I know the flat 3 plug needs to be plugged in, but what if there is not anything to plug it in to??
Dang
Al
no start 87 motor in 90 chassis...
FARTBREF
#3
87 harness
at the ECU plug there are 3 other plugs, 1 wire white/blue, 2 wire and 3 wire plug…if I remember the 3 wire flat plug has to be plugged in, but in this '90 there is nowhere to plug it to…I know there is a work around…cant remember, will search some forums…would rather not change harnesses…
Al
jlevie
#4
The 87 harness is why it won’t start. The START signal to the DME is via C101 on a 9/87 or later car, but via a three pin pigtail to the engine harness on an 87 harness. Rip out the 87 harness (but don’t throw it away) and use the 90 harness and fuel rail connector from the old motor.
It is possible to pull the 87 harness, rip it open and add the tach and START signal wires to C101. Or to rip into the car’s harnesses and rewire to provide those to the three pin connector. But it is lots easier to switch harnesses.
andrew240z
#6
would this be the same with an 87 chassis and 90 motor? switch to the 90 harness and go?
FARTBREF
#7
hmm ya gotta be careful as on early cars there is a wire that goes to ground and will smoke a later harness…I did it an dcut that wire out and the car ran fine, not sure which one it is in the big round connector plug, Levie??
Al
jlevie
#9
FARTBREF wrote:
Cut pin 20 of C101 when using a late harness in an early (before 9/87) car. Understand that you’ll have add the 3 pin connector to the harness.
andrew240z wrote:
In this case nothing need to be done. The wiring harness matches the car. Most of the sensors on the 90 motor will be fine. Only the oil pressure switch would need to be changed to match the harness, if you aren’t running a gage.
andrew240z
#10
Thanks for the info. bought it yesterday, guy gave up on it. turns out the ground strap was loose. A little gas and bam it starts right up. now I gotta figure out what to do with it…