This 1997 Chevrolet K1500 pick up came in with the speedometer, tach and shift indicator not working sometimes. In testing I also found that there were codes stored related to the TCC (Torque Convertor Clutch) and transmission. P0740, P0785 and P1860. This is a pretty common problem but I was looking for a quick simple test that almost anyone could do, to confirm the cause. The simple test is to check for ignition voltage at the “Trans” fuse, #20, 10 amp at the fuse box located at the left (driver’s) end of the dash. No power here with the key on and most likely the ignition switch is faulty.
This fuse is powered by a white wire from the ignition switch. Check there for power as well, with the key on. If power is not present, the only other test is for power on the red wire at terminal D5 of the ignition switch connector. It is easier to just confirm power on both red wires and not worry about terminal designations. For more information on getting to and changing the ignition switch please click here.
No sir, it is not 4WD but I will check the wires by the exhaust. Can that still be the problem if ut us not 4WD….I did notice some wires that may have been touching the exhau, but they led to a O2 sensor. And thanks for you help..I plan on coming back to this site fir info…I even have it bookmarked.
The ignition switch will not cause the fuse to blow. I would suggest looking at the wiring harness near the transmission. Most of the time a harness is laying on the exhaust or on the front drive shaft, if it is 4WD.
I have the same problem with my 96 suburban. I replaced my speed sensor and shift solenoid. I started out by replacing my blown transmission fuse, and when i did and added power it blew again. Even after replacing those parts it still blows the fuse. Is the ignition switch the problem or something else.
Did you do a voltage test with a voltmeter? The voltage may be low enough to cause a problem but enough to light a test light. I have 35 + years of using test lights and can “see” a major drop in voltage while using a familiar test light. Remember that the voltage needs to be checked when the malfunction is present.
I have the same problem with my 1995 K1500, 5.7L. I have checked the transmission fuse and the two red wires going to the ignition switch, all have power. Any other suggestions?