85 c4 code 43
02-25-2012, 03:43 PM
#1
5th Gear
Thread Starter
Member Since: Jan 2012
Location: Boise Idaho
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
85 c4 code 43
Did a recent top end rebuild on my 85 C4. Got everything back together and it fires right up. Once the engine warms up, if I lay into the throttle, the engine hiccups, the SES light comes on, and the car is down on power. Went home and coded it and came up "43" Electronic Spark Control (Knock Sensor). I realized when disassembling the motor the connector for the knock sensor basically crumbled in my hand so I soldered on a new connector. So maybe the sensor itself is bad. $35 later and a new sensor installed and it is still doing the same thing. I'm at my wits end with this one. Could use some help. Anybody have an idea what's going on here?
02-25-2012, 04:35 PM
#2
Le Mans Master
I recently had a code 43 throw due to a bad o2 sensor connection however, first thing I would do is follow the code 43 troubleshooting diagram in the fsm, let us know what that says.
02-25-2012, 04:41 PM
#3
5th Gear
Thread Starter
Member Since: Jan 2012
Location: Boise Idaho
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
troubleshhoting
The troubleshooting diagram shows voltage checks both in and out of the ESC module, which reads the knock sensor back to the computer. Should be under 6 volts. depending on where the voltage goes over 6 volts it could be a bad connection, ESC module or the ECM itself. The messed up part is that none of these were a problem before I took it apart, and I am having a hard time remembering where this one is located.
Last edited by martyp63; 02-25-2012 at 06:40 PM.
02-25-2012, 06:39 PM
#4
Pro
The troubleshooting diagram shows voltage checks both in and out of the ESC module, which reads the knock sensor back to the computer. Should be under 6 volts. depending on where the voltage goes over 6 volts it could be a bad connection, ESC module or the ECM itself. The messed up part is that none of these were a problem before I took it apart.
02-25-2012, 08:40 PM
#5
5th Gear
Thread Starter
Member Since: Jan 2012
Location: Boise Idaho
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
I had the battery disconnected while I changed the knock sensor. That should've reset the ECM. Just to make sure I did do that. Took it for a drive and once the engine is warmed up and the ECM goes to closed loop operation, get into the throttle, the engine hiccups, and the SES light comes on. Check the code and it's still 43. Damn this is frustrating. According to the layout of the circuit the ESC module could be bad, the ECM itself, or there is a fused wire from pin A6 on the ECM to the ESC module. Guess I need to find that fuse and check it out.
