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View Full Version : Need some help with a code 43



joegreen
07-10-2017, 02:07 AM
1988 k2500 with a brand new gm goodwrench tbi 350 and 700r4. On the highway with cruise control on at 65 when it hits a small hill and downshifts from 4th to 3rd the cel will come on with a code 43 (knock sensor). I can get knock counts on tunerpro when i hit the exhaust manifold with a hammer. When im out driving i dont see any knock counts. Not even when starting it up. Also the connection i have between the ecm and tunerpro is pretty crappy. When you are sitting at a red light just idling in gear it shows connection error but the second you hit the accelerator to take off the connection restores. Anyway i need help on what to try next to get rid of this cel from turning on.

joegreen
07-12-2017, 02:43 AM
So the knock sensor ohms out at 3.9k ohms and i am able to see knock counts in tuner pro when hitting the exhaust. Here is a data log that was taken when the light was cleared and when the light turned on. Is there any way to test the esc module?

sturgillbd
07-12-2017, 03:29 AM
You have the wrong knock sensor. If it reads 3.9 k , that sensor is for the later PCM. If you have a 7747 the sensor should be approximately 100k. The 3.9k sensors were used on the 1993 up PCMs with red and blue connectors such as a 16197427.

joegreen
07-19-2017, 04:25 AM
Your right. I put in a 100k knock sensor and the check engine light has not come on since. Thanks