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13 gru 2007 · Code 42 is caused by the ECU not seeing battery voltage showing up on pin 13 when the ECU is trying to run the fuel pump. The connection between pin 13 and the FP power line is in the 1G tech manual and the '90 FSM but missing from the later manuals even though it's still in the wiring.
12 sty 2018 · A code 42 can set with the engine running if the EST line doesn't have a 5V square wave on it. This could be caused by a short to ground on the EST (wh) line. It could also be caused by an open between the PCM and module on the bypass wire (brn/bk).
22 lip 2016 · I can tell you from experience that a code 42 on an OBD 1 GM with throttle body injection is the injectors failing which in turn burns out the spark chip as it tries to compensate. I had an 87 Celebrity that mechanics would try to replace just the injector or the ecm to have it fail, repeatedly.
The code 42 is actually listed as a grounded EST circuit (even in Alldata), but technically speaking, on the LT1 f-body, it is referred to as the Ignition Control Circuit. A code 42 is set when the PCM sees that the signal voltage was unusually low and likely grounded.
29 kwi 2006 · Code 42 is the ESC circuit (module) and it seems like a pretty darn common problem, as I had it when I first did my conversion. Ill look for the flow chart for code 42, its around here somewhere.
18 sie 2010 · Code 42 can be set by a bad distributor module, a bad ECM or wiring problems between the ECM and distributor. A bad distributor module is a common cause for this code. Many stores like NAPA in my area will test the module for free if you bring it in.
27 gru 2011 · Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system. During cranking, the timing is controlled by the ignition module and the ECM grounds the EST line.
