P1639 P1635 and ecm b fuse blowing

[opiefavors]

My 2000 yukon xl 2500 is having some issues. I have both codes of P1639 and P1635. Also the ecm B fuse keeps blowing.

I know the ecm B fuse has to do with the fuel pump but what else is on this circuit? A friend said its the fuel pump but Im not one to just go replacing parts.(the pump is quite loud though, pretty sure I'll be replacing it soon anyways.

This truck is my daily at the moment and I really need it to be reliable. Thanks.

 

[opiefavors]

Could a bad pump cause all 3 symptoms?

 

[SLCHOE]

Disconnect the fuel pump relay and put in a new 30A ECM B fuse. Turn the key. If the fuse still blows, there is a problem with your ECM and specifically the 5V reference circuit driver shorting to ground internally.



If this is the case, there is a chance that the ECM is ok but one of the sensors being fed the 5V or shorted to ground.

The next step:



Disconnect all of these sensors:

• MAP sensor
• EGR valve
• Throttle position (TP) sensor
• Fuel level sensor
• Fuel tank pressure sensor

 

[opiefavors]

The fuse dosnt blow instantly. It blows after driving for about a day. Its random. Also the codes come and go as they please lol.

 

[opiefavors]

How do I check all those sensors. What does disconnecting them do?

Sorry if I sound stupid. Electronics and sensors are not my thing.

 

[SLCHOE]

How do I check all those sensors. What does disconnecting them do?

Sorry if I sound stupid. Electronics and sensors are not my thing.

Disconnecting them takes them out of the scenario. Adding them one by one will tell you which one (or possibly ones) are your issue (the fuse will blow).

You say it takes time to blow the fuse so this simple approach probably wont work if it's not intantly blowing at key on.

Based on what I gather from your situation, it needs to go to a shop with a sharp tech with a scope. You wont be able to DIY this one. Too many variables involved and special (and expensive) tools needed to do the proper diagnostic. Even with all of that, it may take some time to figure out.

 

[opiefavors]

Thats what i was figuring. That sucks. Cause i dont have the extra money for it at the moment.