TBI sensors

[rfmaster]

It is normal for SES light to be on when engine is OFF - ignition ON (run position).

ECM goes through power on self test (POST) when you move ignition key from off into run position. SES should go from solid ON blink off and turn solid ON through initial engine cranking. At the same time fuel pump is powered up for about 2 - 3 sec.

Make sure that you're connecting correct two pins on ALDL connector -> A & B. SES light will blink code 12 three times followed by other DTC codes (if any), but it must blink Code 12 first! This tells you positively that ECM is in diagnostic mode.

Once engine starts running (400+ RPM) SES should go OFF and stay off until engine is shut down. If you are getting engine stall (i.e engine RPM falls below 400RPM) you may see SES come on or blink. This usually happens when ECM looses DRP signal from dizzy. TBI ECM must have DRP signal from dizzy to fire injectors! This is why malfunctioning dizzy will create havoc.

Checking fuel pressure is not that difficult, but you'll need to have FP gauge with TBI specific adapter. You can find inexpensive reasonably priced, decent units on ebay ( 230776223174 ). Factory spec is 9 to 13 PSI.

//RF