1988 Chevy Silverado code 42

Tiny
CARPNTA
  • MEMBER
  • 1988 CHEVROLET SILVERADO
Computer problem
1988 Chevy Silverado V8 Two Wheel Drive Automatic

code 42 on scanner, replaced ign module, spark control module, then on the advice of expert replaced ecm. No help. With the est bypass disconnected it starts and runs great, reconnect the bypass connector revs up great. Shut the engine down restart and runs like c**p. Can the prom or calpak chip cause this or is the problem elsewhere?
this is a calif smog motor w/tbi

thanks
Do you
have the same problem?
Yes
No
Thursday, January 21st, 2010 AT 9:27 PM

7 Replies

Tiny
RACEFAN966
  • EXPERT
It seems that code 42 is related to the ground of the control module mounted on the distributor. Now what I need you to do is disconnect the 4 pin connector to the distributor and use the pic below to find pin A and check it. What you do is use a digital multi meter and ohm between term A and gound is there continuity? Get back to me with what you find. We will check the ESC Module next if this checks ok. I do need to know what size truck 1/2 ton or ? and what engine as the 305 has a different ESC then the 350 and so on.


http://www.2carpros.com/forum/automotive_pictures/249564_Graphic_189.jpg

Was this
answer
helpful?
Yes
No
Friday, January 22nd, 2010 AT 10:16 AM
Tiny
CARPNTA
  • MEMBER
Do I check on the ign module or the connector side?

The eng is a 350. 1/2 t
Was this
answer
helpful?
Yes
No
Friday, January 22nd, 2010 AT 1:17 PM
Tiny
CARPNTA
  • MEMBER
Checked the a term. On the ign module, checks ok
Was this
answer
helpful?
Yes
No
+1
Friday, January 22nd, 2010 AT 2:16 PM
Tiny
RACEFAN966
  • EXPERT
Ok so I need you find the ESC module shown in the pic below. Before we get to far with this I also need you find the knock sensor on the passanger side of the engine block see pic. Now hook up a timing light and tap the block with a hammer near the knock sensor what does the timing do?

ESC Module,


http://www.2carpros.com/forum/automotive_pictures/249564_ESC_Module_1.jpg



Knock Sensor,


http://www.2carpros.com/forum/automotive_pictures/249564_50494_1.jpg

Was this
answer
helpful?
Yes
No
+1
Saturday, January 23rd, 2010 AT 9:02 AM
Tiny
CARPNTA
  • MEMBER
Well I haven't been able to do that knock sensor test, nobody around to give me a hand, I can't hammer on the blk from the top to much in the way, so I just replaced it, along with the map sensor.
It's kind of frustrating it runs great with the set timing connector off. Could it be a worn out dist. It has 250K plus mi. On it?
Was this
answer
helpful?
Yes
No
Sunday, January 24th, 2010 AT 5:37 PM
Tiny
CARPNTA
  • MEMBER
Solved the problem myself dist. Is shot.
Was this
answer
helpful?
Yes
No
+1
Monday, January 25th, 2010 AT 7:07 PM
Tiny
RACEFAN966
  • EXPERT
So the distributor shaft was worn? Great job glad it is fixed. Have a great day.
Was this
answer
helpful?
Yes
No
+1
Monday, January 25th, 2010 AT 7:17 PM

Please login or register to post a reply.

Recommended Guides