How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Cat Man Your Own Question
Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8762
Experience:  I am ASE Master Truck Certified.
30708357
Type Your Medium and Heavy Trucks Question Here...
Cat Man is online now
A new question is answered every 9 seconds

Hey Cat Man, I have another cat problem. Just finished a

Customer Question

Hey Cat Man, I have another cat problem. Just finished a inframe on a 3406E sn# ***** By mistake I crossed the cam sensor 3 wire plug with the other sensor wire with the same plug behind the air compressor. Cant think of anything else that would now
make it not start. I have no way to scan the computer but im thinking I missed it up or one of the sensors. Any ideas?
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Cat Man replied 1 year ago.
Thanks for asking your question and requesting me. I will try and help you out.
Crossing up the sensors should not hurt anything.
So this is the first crank attempt after the inframe? And it will not start?
Customer: replied 1 year ago.
Yes, Fuel pressure hand pumps up tight, Cranks over strong and has good compression. No smoke or even a attempt to start. timing sensor and turbo outlet sensor were crossed while cranking? Inframe was for linners but it ran great.
Expert:  Cat Man replied 1 year ago.
Thanks for the information.
Does the yellow check engine light come on when the key is turned to the on position?
Customer: replied 1 year ago.
yes......it comes on for a few seconds and then goes out
Expert:  Cat Man replied 1 year ago.
Thanks for the information.
If the light is coming on. The ECM is receiving power and functioning. That's good news
Next I would try checking AC power to the injectors while cranking. You should have between 20-40 AC. If you do the ECM is functioning fine, and it's getting a tdc and rpm signal. If it is not making AC, there is either a tdc RPM problem , ECM problem , or low power to the ECM while cranking. The ECM must have at least 7.5 volts DC to operate.
Please reply back if you need more help or have more questions. I am happy to assist.
Customer: replied 1 year ago.
I checked the injector power using a digital AC voltmeter.....it does not flash any power at all.
Expert:  Cat Man replied 1 year ago.
Thanks for the information.
If there is no power to the injectors while cranking. you have either low power to the ECM while cranking, a bad engine speed timing signal, or a faulty ECM.
I have seen the batteries disconnected for an inframe and cause the ECM to lose memory. This is caused by the back up battery inside the ECM has failed. Then when the batteries are disconnected, it may lose memory.
Unfortunately the only way to verify is to connect a service tool like Cat ET.
Please reply back if you need more help or have more questions. I am happy to assist.
Customer: replied 1 year ago.
Is the CAM sensor the one to give the ECM its RPM signal? If it's ok.....would the fix for the ECM be a replacement or reporgramming? Which PIN number would be my ECM input to check?
Expert:  Cat Man replied 1 year ago.
Yes. The Cam sensor is the engine speed timing sensor that tells the ECM RPM and TDC.
The ECM can be reprogrammed while on the engine with power. The only problem is if the batteries are disconnected again. It will lose memory. Most folks replace the ECM with a new so the back up battery will hold memory if the batteries are disconnected.
6 and 4 are the positive power input to the ECM 5 is the ground. These pins are on the lower ECM truck harness connector.
Let me know if you need more help
Expert:  Cat Man replied 1 year ago.
Hey. I just wanted to see how things were going. Please let me know if you need more help. I am happy to assist. If my information was helpful, please leave a good or higher rating so that I receive credit. Thanks.

Related Medium and Heavy Trucks Questions