Optical sensor

[snarl95]

Anybody have one they could let me borrow. I keep getting codes 17,18,35,36 randomly.

 

[Rockabillyrat]

I don't have one, but thoes 4 codes together are usually signs of a bad injection pump. Gm issued a TSB stating to replace it if those codes are found. Obviously you want to check the wiring and for any air in the fuel. But everytime I see that combination of codes on a customers truck its been a bad pump

 

[snarl95]

what goes bad in the pump? I put it in Feb of 2021.

 

[snarl95]

or a pump to borrow.

 

[Rockabillyrat]

Here is the TSB. But if you replaced the pump with a GOOD reman it should have all the upgrades already.

 

[snarl95]

The other thing is when it goes into defuel mode it runs better, no power but runs smoother. Thank you for posting that but I can't enlarge it to read.

 

[Stoney]

I'll post pic of the pump I have. And of the I.d. tag. If it will work I'll ship it to you.

 

[ak diesel driver]

Have you tried doing the OS/CPS tests?

 

[snarl95]

It starts and runs with the OS unplugged haven't tried the cps yet.

 

[MrMarty51]

It starts and runs with the OS unplugged haven't tried the cps yet.

I’m not sure but, I think that indicates that the Op sensor is bad.

 

[ak diesel driver]

No that just means the CPS is good

 

[snarl95]

Unplugged OS truck started hard but ran. Plugged OS in and unplugged CPS truck cranked but no start.

 

[dbrannon79]

if it will start, it usually takes a little bit longer cranking time for it to fire off with one of the two disconnected. do you have a scanner to read if you are getting rpm signal?

 

[MrMarty51]

Unplugged OS truck started hard but ran. Plugged OS in and unplugged CPS truck cranked but no start.

To Me it sounds like the OP is not functioning.
I will let the others with more smarts confirm or not that statement.

 

[ak diesel driver]

If you have a scanner that will show idle fuel rate it's actually not to hard to change the OS

 

[Stoney]