check engine light

[dunehopper502]

my 90 k5 blazer keeps setting a code 42, light will intermittenly go on and off tried to clear by disconnecting battery but came back on....
any suggestions on where to start diagnosing? alls i know so far is it is an est issue for my timing....i have msd distributor,6a box,msd coil and msd wires
thanks

 

[ryan22re]

my 87 kept setting the esc code...i found the knock sensor wire pinched under the starter...just a thought

ryan

 

[dyeager535]

I believe others have had the code 42 problem, losing the MSD solved it.

Not saying you need to pull it, just keep that in mind while trying to figure it out.

 

[dunehopper502]

well ive had msd for a couple of months now and this just started,could it still possibly be the problem, i was told my pcm was bad from the vibration of the boggers

 

[dyeager535]

People love to blame what they don't understand. ECMs are almost never bad.

Dunno what causes code 42 in TBI trucks, but heres the TBI code 42 test procedures out of a Camaro manual. Let me know if wire colors are the same.

Code 42

BTW, pulling the ECM fuse is a lot better than pulling the battery cable. Contrary to what most say, 10 seconds seems to be more than enough time to clear the ECM codes.

 

[sweetk30]

i killed my 6al box in 6 months from bias tires even on the supplyed mounts. got warrentyed and upgraded to offroad box . no more problems.

 

[Thunder]

Code 42 is pretty common trouble code with 6al boxes. Also the MSD distributor modules are not as good as AC delco. The module may be throwing the 42. Try bypassing the box and hooking up like stock to see if that works. If you still get a 42 the pickup coil or the module are probabally going out.
If the 42 goes away after disconnecting the box you found your trouble.

 

[dunehopper502]

awesome guys thanks for the great info, give me something to do this weekend after the woodward cruise of course......