Mechanics

CHEVY CHEVY 1500 CHECK ENGINE LIGHT?

1991 Chevrolet Truck

Engine Performance problem
1991 Chevy Truck V8 Two Wheel Drive Automatic 153000 miles

My 1991 chevy 1500 two wheel drive check engine light turns on after the truck is warm. I have to drive at least 50 or 60 miles before it turns on then it is off the next time I start it. Any ideas?
Thanks
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Kurto_15
January 24, 2009.



Jump A to B ALCL and read off the flashes on the CEL and comeback with code/s


http://www.2carpros.com/forum/automotive_pictures/12900_GM_ALCL_19.jpg


Rasmataz
Jan 25, 2009.
Thanks I just did that and got a code 43 which is the knock sensor or electronic spark control circuit fault. Anyone have any similar problems?

Tiny
Kurto_15
Jan 25, 2009.
CODE 43, ESC (ALL EXCEPT 4.3L TURBO & MODELS W/4L80-E TRANS)
NOTE:Test numbers refer to test numbers on diagnostic chart.

If conditions for a Code 43 exist, Scan tester will display YES. A knock signal should not exist at idle unless an internal or system problem exists.
Determines if system is functioning. Usually, a knock signal can be made by tapping on the exhaust manifold. If knock signal is not made, try tapping on engine block near sensor. On models with automatic transmission, it may be necessary to place gear selector lever in Drive.
Because Code 43 sets when the signal voltage on the spark retard line remains low, this test should cause the signal on that line to go high. The 12-volt signal should be seen by the ECM as a no knock signal if the ECM and wiring are okay.
This test determines if the knock signal is detected on the sensor-to-controller line or if the ESC module is at fault.
If sensor line is routed too close to secondary ignition wires, the ESC module may see the interference as a knock signal.
This checks ground circuit to module. An open ground will cause the voltage on the monitored line to remain constant at about 12 volts. This would cause the Code 43 functional test to fail.
This should generate a knock signal to the controller. This determines if the ESC controller is operating correctly


http://www.2carpros.com/forum/automotive_pictures/12900_code43_1.jpg




http://www.2carpros.com/forum/automotive_pictures/12900_code431_1.jpg




http://www.2carpros.com/forum/automotive_pictures/12900_code432_1.jpg




http://www.2carpros.com/forum/automotive_pictures/12900_code433_1.jpg


Rasmataz
Jan 25, 2009.