|
06-06-2009, 09:07 AM | #1 | |
Registered User
Join Date: Oct 2003
Location: OC CA
Posts: 1,374
|
Re: Tbi swap build thread
Quote:
1227747 ECM uses starter motor (aka cranking) signal and DRP signal from dizzy to enable start up sequence, which includes enrichment sequence if CTS indicate cold coolant temperature. Now, the oil pressure signal is really a fuel pump voltage monitor. In these early EFI systems GM put a primitive back to keep fuel pump operating by installing (normally open - NO) oil pressure switch in parrallel with FP relay contacts. If FP relay fails, but as long as oil pressure is above 4-6 PSI the oil pressure switch will keep current flowing to the fuel pump. FP relay (kinda) gets tested during POST sequence - ignition key off - on. SES light will go from on - off - steady on if all is well until engine starts. During POST ECM will try to power FP for about 2 seconds and shuts off. However, ECM monitors the FP relay switched side voltage when DRP are present and will set Code 54 if the voltage is low. Official description------------> Powertrain Controls - ECM/PCM Code 54 Fuel Pump Circuit CODE 54 - FUEL PUMP CIRCUIT (LOW VOLTAGE) CIRCUIT DESCRIPTION : The status of the fuel pump CKT 120 is monitored by the ECM at terminal "B2" and is used to compensate fuel delivery based on system voltage. This signal is also used to store a code if the fuel pump relay is defective or fuel pump voltage is lost while the engine is running. There should be about 12 volts on CKT 120 for at least 2 seconds after the ignition is turned, or any time reference pulses are being received by the ECM. Code 54 will set if the voltage at terminal "B2" is less than 2 volts for 1.5 seconds since the last reference pulse was received. This code is designed to detect a faulty relay, causing extended crank time, and the code will help the diagnosis of an engine that "Cranks But Will Not Run." If a fault is detected during start-up, the "SERVICE ENGINE SOON" light will stay "ON" until the ignition is cycled "OFF". //RF
__________________
"The Beast" 1975 Chevrolet C20 longbed 350/700R4! with 3inch body lift Dual Flowmasters Super 40's! TBI retrofit completed (2007-07-29) New 383CID (+030) 08-304-8 9.5:1CR x36,005 (2012-12-17) |
|
06-06-2009, 05:05 PM | #2 | |
Registered User
Join Date: May 2009
Location: Space City! (TX)
Posts: 46
|
Re: Tbi swap build thread
Quote:
Mark |
|
06-06-2009, 05:26 PM | #3 |
Registered User
Join Date: May 2009
Location: Space City! (TX)
Posts: 46
|
Re: Tbi swap build thread
FB72: I made a mistake... terminal C2 is on the larger of the two ECM connectors (32 pin, not 24) - sorry.
|
Bookmarks |
|
|