Help needed: Code 42 - Electronic Spark Control Error - ZR-1 Net Registry Forums

QB93Z · 04-27-2012

We are trouble shooting a Code 42 - Electronic Spark Control Error on a 1991 ZR-1 that was rebuilt after a cam chain failure.

I don't know if this problem is related to an idle speed control problem that we are also trouble shooting. The symptom of that are that the idle rpm oscillates from ~950 to ~1100 with about a 10 second period. During the oscillations, spark advance measured by a Tech 1 is also oscillating.

The Service Manual indicates that Code 42 signifies that the ECM is not seeing the correct voltage on the EST signal from the Ignition Module. After working through the trouble shooting flow chart, the problem may be a failed Ignition Module. Based on how rare IM failures are, I am looking for suggestions of other things to look at. We did verify circuit continuity and connector condition which are other possible causes of Code 42.

The Code 42 can be cleared by the Tech 1, but is set again as soon as the engine starts.

Has anyone had experience with Code 42?

XfireZ51 · 04-27-2012

Jim,

Code 42 us pretty universal in GM world having to do w ignition module. I guess you swap out modules and see what happens. On L98 motors that was pretty cheap to do.

Pete · 04-27-2012

If you put a scanner on it,check to see if it's pulling timing/knock retard.

Check knock sensor wire make sure it's not melted to the header or touching ground and or make sure it's connected to the knock sensor, check knock sensor make sure it's not too tight or bad knock sensor.

Pete

GOLDCYLON · 04-27-2012

Quote:

Originally Posted by QB93Z

We are trouble shooting a Code 42 - Electronic Spark Control Error on a 1991 ZR-1 that was rebuilt after a cam chain failure.

I don't know if this problem is related to an idle speed control problem that we are also trouble shooting. The symptom of that are that the idle rpm oscillates from ~950 to ~1100 with about a 10 second period. During the oscillations, spark advance measured by a Tech 1 is also oscillating.

The Service Manual indicates that Code 42 signifies that the ECM is not seeing the correct voltage on the EST signal from the Ignition Module. After working through the trouble shooting flow chart, the problem may be a failed Ignition Module. Based on how rare IM failures are, I am looking for suggestions of other things to look at. We did verify circuit continuity and connector condition which are other possible causes of Code 42.

The Code 42 can be cleared by the Tech 1, but is set again as soon as the engine starts.

Has anyone had experience with Code 42?

With the plenum pull any possibility a pin was bent when connecting to the ignition module on the underside of the plenum? Also Id check the harness to the same module for roaching. GC

QB93Z · 04-28-2012

Thanks for all the responses. There was no knock retard. We checked all the pins and connectors. I now suspect that it may be a ground problem and we will look into that possibility.

Jim

oricale · 05-01-2012

I went ahead and replace the knock sensor and checked the wiring to it...no change
What troubles me the most. Is the lack of power..ALSO.... When I get on it with LOW RPMs I am seeing smoke...all this leads me to believe this is a timing issue..but I am at a loss becuase I have checked everything I know of....I still have the fluctuating idle and code 42 as well!....HELP!!!!

GOLDCYLON · 05-01-2012

Anybody as Mark or Corey ? Anybody have an ignition module to loan to test? I do not

tomtom72 · 05-02-2012

I have a spare DIS box. I'll separate it from my spare plenum and box it up for shipping. Oh, I forgot this...I can lend it to you .

I had this happen to me...this is a fwiw btw

....when I was not paying attention and installed the DIS main harness plug, the one with a billion wires in it, upside down. I bent a pin, just one pin, and I couldn't see it using my mirror either. Had to repull the plenum to discover what I had done.

Tom

thomastom72@aol.com

oricale · 05-02-2012

PM sent!....

tomtom72 · 05-02-2012

PM answered!

Tom

04-27-2012	#1
QB93Z Join Date: May 2007 Location: Westminster, Maryland Posts: 3,684	Help needed: Code 42 - Electronic Spark Control Error We are trouble shooting a Code 42 - Electronic Spark Control Error on a 1991 ZR-1 that was rebuilt after a cam chain failure. I don't know if this problem is related to an idle speed control problem that we are also trouble shooting. The symptom of that are that the idle rpm oscillates from ~950 to ~1100 with about a 10 second period. During the oscillations, spark advance measured by a Tech 1 is also oscillating. The Service Manual indicates that Code 42 signifies that the ECM is not seeing the correct voltage on the EST signal from the Ignition Module. After working through the trouble shooting flow chart, the problem may be a failed Ignition Module. Based on how rare IM failures are, I am looking for suggestions of other things to look at. We did verify circuit continuity and connector condition which are other possible causes of Code 42. The Code 42 can be cleared by the Tech 1, but is set again as soon as the engine starts. Has anyone had experience with Code 42?

04-27-2012	#2
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,683	Re: Help needed: Code 42 - Electronic Spark Control Error Jim, Code 42 us pretty universal in GM world having to do w ignition module. I guess you swap out modules and see what happens. On L98 motors that was pretty cheap to do.

04-27-2012	#3
Pete Join Date: Dec 2003 Location: Chicagoland,IL Posts: 2,667	Re: Help needed: Code 42 - Electronic Spark Control Error If you put a scanner on it,check to see if it's pulling timing/knock retard. Check knock sensor wire make sure it's not melted to the header or touching ground and or make sure it's connected to the knock sensor, check knock sensor make sure it's not too tight or bad knock sensor. Pete __________________ '91 #1635 PoloGreen 350 LT5 11.09 @ 129.27 11.04 @ 128.86 474RWHP 400RWTQ http://www.youtube.com/watch?v=SFNFOhGGlR4 http://www.youtube.com/watch?v=ZlRIOMwaDYY https://sites.google.com/site/peteszr1garage

04-28-2012	#5
QB93Z Join Date: May 2007 Location: Westminster, Maryland Posts: 3,684	Re: Help needed: Code 42 - Electronic Spark Control Error Thanks for all the responses. There was no knock retard. We checked all the pins and connectors. I now suspect that it may be a ground problem and we will look into that possibility. Jim

05-01-2012	#6
oricale Join Date: Oct 2011 Location: STAFFORD VA, Posts: 576	Re: Help needed: Code 42 - Electronic Spark Control Error I went ahead and replace the knock sensor and checked the wiring to it...no change What troubles me the most. Is the lack of power..ALSO.... When I get on it with LOW RPMs I am seeing smoke...all this leads me to believe this is a timing issue..but I am at a loss becuase I have checked everything I know of....I still have the fluctuating idle and code 42 as well!....HELP!!!!

05-01-2012	#7
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,120	Re: Help needed: Code 42 - Electronic Spark Control Error Anybody as Mark or Corey ? Anybody have an ignition module to loan to test? I do not __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V

05-02-2012	#8
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,609	Re: Help needed: Code 42 - Electronic Spark Control Error I have a spare DIS box. I'll separate it from my spare plenum and box it up for shipping. Oh, I forgot this...I can lend it to you . I had this happen to me...this is a fwiw btw....when I was not paying attention and installed the DIS main harness plug, the one with a billion wires in it, upside down. I bent a pin, just one pin, and I couldn't see it using my mirror either. Had to repull the plenum to discover what I had done. Tom thomastom72@aol.com __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member