Join Date: Mar 2004
Feedback Score: 0 reviews
Re: Cat 3126 problems
On my KW's, Freighliners, and CCC trucks the cruise control/check engine light WILL point you in the right direction. A 39 flash WILL send you to the IAC valve. A 31 Flash WILL send you to the lost speed signals. Our Cat distributor used to ask what codes were flashing via the check engine light, but have since given me a pocket tec to use. Pages 58 thru 66 in the C7 operation manual (only one handy and identical to 3126E manual), list the procedure for retrieving the codes using the cruise control switches, what the codes are, and the consequences. Usually though, in the case of the speed sensors, with the engine running, the check engine light comes on, depending on how the engine is programmed, the engine may run normal or power down. If the sensor/wiring is bad, it might still run, but once you turn it off, it will not receive a signal, and thus the no start. Here is where a scanner or pocket tec will show you the cruise control flash code, and cross it over to a cat code. The IAC will flash a code 39 with the cruise, but show up as a 164-11 on the scanner. The cruse flashes will point us in the right direction while troubleshooting,and has helped me and my cat distributor repair my problems over the phone, but it is not the see all the scanner is. It will give you an idea where the trouble lies.
Another thought, the problem could be something as simple as the main fuse going to the ecm! Had one of the off the wall chassis that the factory put too small of fuse in, and the engine kept quitting - no codes - no flashes - I think the factory called for a 10 amp and cat called for a 25 amp (long time ago) changed fuese and problem went away.