1993 s-10 ECM support

[bigrob65]

I replaced the ECM on my 1993 /s-10 4X4 with a 4.3 engine. The service engine light still flashes all of the time. The engine will start but when shut off it will not start until battery is unhooked for 10 sec. the light continually flashes no matter what. I have a snap on 2500 scanner and can not clear code to recheck system. Code 55 ECM still shows even though replaced. Need help from anyone who knows why and what I should do .
Thanks, BIG Rob

[ctesla]

hey Rob,
Welcome to AF!
code 55 can be ECM/O2/VSS(rearABS), etc.
possibly faulty ground.
have you checked the voltage on terminals 21 & 22?

I have schematics in my shop.
will check tonight. but if you've already swapped ECM, may swap PROM chip, check for faulty ground or burnt wires on O2s, and maybe vacuum on TPS switch.
or check vehicle speed sensors (as they run on this circuit as well).

hope this helps,
-I'll post back with specs,

chris
nrt racing

[OverBoardProject]

Chris;

Just wondering if nrt racing has a web site?

Thanks
Stu

[ctesla]

Stu,
no web site yet.
sent you a PM on it.
if that motor home is roadworthy, and you ever want to holiday in Colorado, let me know. got MORE than enough acreage... and anybody RODDING an Essex has got to be just psycho enough to work with (not for) me. if you need assist locating parts, let me know.


bigrob,
GM tech manual stips:
if you had a heater core leak, or coolant temp sesnor, or windshield leak, to first check ECM plug-in connector for calcium or other built up debri not allowing contacts.
if not-
disconnect O2 sensor, and while at idle
check voltage on ECM terminals FROM#21 TO 22
>6 volts= turn OFF ign, disconnect meter, ign ON check for
voltage again: if Volts, then check for short in B+ wire to Terminal 21
-if 0volts, check ECM connection.

<4 volts= check for ground circuit @21 which includes TPS, TPS vacuum, VSS(speed sensors)

4-6volts= ign ON, eng OFF, check volts from O2 power lead wire (purple if unheated model)

checking O2 volts, if over 1 volt, then could be ECM harness connector Terminal #9, or back to BAT.
or could be open circuit from Terminal #14 to grounding.

if under 1volt, then intermittent ground in Terminal 21, TPS, and/or Vacuum sensors (any), or just faulty O2.

hope this helps,
chris
nrt racing


---and STU!!!
just talked to you on the phone. had a wonderful chat. can't wait to do business with you.
AND! get you way better than 12mpg.