Z28MJ

so me engine died last Saturday and at first I thought it was the fuel pump, then it looked like there was a wiring issue (something was not working right at the relay) so I jumped the relay to see if it worked....it did. I built a temporary switch to control the pump (with the jumper it was running all the time). I put it all back together (dropped the pump back into the tank, put the interior back..etc) and tried to start it, nothing. so I get my OBD II scanner out to scan for codes and I am looking at it when my dad comes out to see how it is going, so I crank the engine.......it starts right up (at this point I am like wtf?) so I unplug my scanner......the engine dies. I try to start the engine and it just cranks, so I replug in my scanner and try to start it and it starts right up. Why would the engine only work if I have the scanner plugged in???????

Z28MJ

I checked all the grounds and they all seem good...

Z28MJ

well I am just going to take it to the dealer and be done.

Old Geezer

iTrader: (3)

Sounds like the pcm is being fed thru the ALDL power.....

sreve

iTrader: (3)

I'm thinking grounded thru it.

ALDL
2 serial data
4 chassis grd
5 sensor grd
16 pwr

Make sure 5 is grounded scanner could be providing grd thru 4.
5 is G110 rear of left cyl head.

check them right at the DLC

Z28MJ

the ground on the back of the head is still tight, what is DLC and ALDL? sorry I am not good with these computer systems

sreve

iTrader: (3)

DLC and ALDL?

Assembly line data link
Data link connector
same differnce

Z28MJ

ok I thanks. I checked them and they all worked