I pulled a stored code 42 - Cylinder Select Error. Anybody know anything about this? I did a MAF>SD swap not to long ago and wasn't exactly sure what to do with the Cylinder Select wire coming out of the ECM. Does this have something to do with it? In the book this says this could also be Bad ECM or MEMCAL. The engine is out of an '85 IROC. I replaced the 165 ECM with a 730 ECM out of a '92 Z28. I had a custom chip burned to disable VATS and some other mods. Could this have anything to do with it? What does this code mean as far as drivability? Any info would be greatly appreciated...:hail:

 

I think 42 means your EST wire was disconnected or the computer couldent communicate with the advance module.

 

Code 42 on my car is the EST circuit. Which can be 1 of 4 things. Either a 1) bad ECM 2) Faulty ignition module 3) circuit 423 shorted to ground (tan and black wire) 4) circuit 424 open (white wire). Both wires plug into the back of the distributor, along with a white/purple wire and blue/red wire. All 4 go into one pig tail. I get a 42 also. soft code though. Check engine light isn't on, but when i check thru the aldl i get a 42. My code is intermitint, so i think one of my circuits are bad , cause one day i'll get a 42 and then the next day it's gone. One of these days i am just gonna steal both wires off of my TBI harness and repin them.

 

The EST wire was connected when I checked the codes so that's not it.

Apparently this code coincides with my starting problem of not firing up unless the EST bypass wire is disconnected. I have since put in a brand new ignition module and coil so I don't think those are the problem. I don't think my ECM is faulty either so I guess at this point in time I will just have to recheck the harness.

Anything else specific I should check like the voltages at those different wires?

 

The ECM expects to see no voltage on the EST whn the inngiton modual grounds the EST signal. If the ECM sees a voltage, it sets code 42 and will not go into est mode
when the est is reached, about 400rpm, and bypass voltage applied, the EST should no longer be grounded in the ingition modual, so the EST fvoltage should bevarying.
If the bypass line is open or grounded, the ignition module will not switch to est mode so the est voltage will be low and code 42 will be set.
If the est line is grounded, the ingnition moduale will switch to EST but, because the line is grounded, there will be no EST signal. A code 42 will be set.


does that help? PM me and Ill give you away to fix the problem.

 

Waz up. code 42 is with the control moudule EST circuit the white wire off your distributor to the ECM should have 1.5 to2.8 volts at idle the pin on the ECM is D4 or B4 cant remember which just hook a jumper off a dig meter to it when EST is bypassed it will be a low voltage usually less than .4 volts. The only thing I can recommend is dont disable it and drive it one it wont have no power two if it detonates you now own junk. Make sure the control module in the dist. is for the same model as the ECM.