SUV was running great but broke the timing belt. I did a valve job but when done is not firing on two cylinders (same coil). Have replaced everything -- coils, ignition controller, crank and cam sensors, and the computer. I run the problem down to the connection between the crank sensor and the computer. Two of the prongs have connectivity (blue light on tester), but the third (on the dead coil) is open (no blue light on tester). However, the wire color (black with red stripe) on the bad sensor lead does not appear on the computer harness -- there is no black with red stripe wire on the computer harnerss! How the heck does the wire color change from end to end through the wiring harness fron the sensor to the computer? Anyway, to troubleshoot further I need to know which computer pin goes to the crank sensor. Also, any other idea on what could cause the problem?
-Anyway, to troubleshoot further I need to know which computer pin goes to the crank sensor.
See below for a 24 valve engine
October, 23, 2012 AT 2:07 PM
Thanks. I am not an expert and the one diagram provided is not enought for me to understand the situation. Unless the blocks on the top are the computer, the connection to the computer from the blk-red from the crank sensor is not shown. But the block on the top right (connection from blk-red on crank sensor) shows blk-red wires and the computer has none of them connected, so I'm figuring the blocks on the top are not the computer pins.
Can you tell me what the blocks at the top are, and where the blk/red from the crank sensor exiting the diagram to the left goes? Can we run the blk-red on crank sensor to the correct pin on the computer?
More importantly, do you have any idea what could cause two prongs of the crank sensor connector to show connectivity (blue light on tester), but the blk/red to be dead (no light on tester, no spark on two coils driven by that sensor signal). That is the bottom line -- what to do next.
October, 23, 2012 AT 11:20 PM
What made you replace all those things over a broken timing belt-Shouldn't be nothing wrong w/the wires on the CPS-try checking the CPS resistances-as per the wiring diagram this is all I got-BTW is it a 24 or 12 valves
October, 24, 2012 AT 4:13 PM
It is a 24 valve 3.0 V6. The engine was running fine (quite well really) but overheated when it broke down (the temp on the inticator shot up just as the breakdown occurred). Once I put the rebuilt heads on and the engine back together, one of the coils (two cylinders) was not firing. Four cylinders were firing indicating that the timing was set right. So I began to trouble shoot the ignition problem. One thing after another did not solve the problem, so now everything in teh ignition circuit is new -- coils, computer, ignition module, crank and cam sensors. But the same problem still occurs -- one coil is dead. Swap the coils, same thing. When I pull off the crank sensor cap -- on the side going to the computer -- the two working leads show connectivity (blue light on the tester) but the non-functioning lead shows no connectivity (no blue light on the tester). That is where it stands now.
October, 24, 2012 AT 9:59 PM
Do you have a blue light on the black and red on the camshaft sensor?
October, 25, 2012 AT 2:45 PM
Nope, blk/red is dead on cam and crank sensor leads. The other two leads show connectivity on both.
October, 25, 2012 AT 10:42 PM
Check that wire back to the computer
October, 28, 2012 AT 8:53 PM
That is what I am trying to do. The wire goes into a harness within a corrugated cladding and presumably through the firewall to the computer in the passenger compartment. How do I go about checking it back to the computer? Can you tell me which computer pin that blk/red wire connects to?