Car just threw a code 42

[rev. 3:11]

Car just threw a code 42 when I drove it today, the only thing I've done is change the plugs (2 weeks ago.) &
installed new pads & rotors yesterday...
Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system.
Typical causes for this code include:
1) BYPASS line is open or grounded
2) EST line is open or grounded
3) PROM or CALPACK not seated properly in the ECM
4) Poor connections between ignition module and ECM
5) Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise)
6) Faulty or incorrect ignition module
7) Faulty ECM
Which tells me not a lot
Where do I start checking!?!
TIA
D

 

[GNVenom]

Ignition module connector. Those are going bad left and right these days. 25+ years old, they weren't designed to last this long.

 

[rev. 3:11]

Jiggled & tightened it, code gone!
Thx, John!
Darrell

 

[TURBOPOWERED68]

Jiggled & tightened it, code gone!
Thx, John!
Darrell

Jinggled & tightened What?

 

[rev. 3:11]

Ignition module connector/harness under coil pack, the 7mm (?) nut,
still chasin' a code 23, already tried 2 IAT sensors; thinkin' its a bad wire

 

[TURBOPOWERED68]

Ignition module connector/harness under coil pack, the 7mm (?) nut,
still chasin' a code 23, already tried 2 IAT sensors; thinkin' its a bad wire

thanks for the reply

 

[rev. 3:11]

 

[2QWIK4U]

Where is the bypass and est line that it is refering to? Want to make sure I'm correct,the spark control module is flat mounted on passenger fender?

 

[TurboBuRick]

White wire (pin a) on the module plug. Runs back the the ecm pin b4.

 

[RmvBfrFlght]

Where is the bypass and est line that it is refering to? Want to make sure I'm correct,the spark control module is flat mounted on passenger fender?

The flat box on the fender mount is the knock filter. The ICM is under the coils on the back of the engine. This is where the EST & bypass wires are.

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