Truck won't give Check engine light codes

The reason I was asking is because, theoretically, California emissions trucks don't have that service interval reminder built into the speedometer - those are the grounds for it that you are switching under the dash. That's not to say that somebody couldn't have bought a non-Calilfornia speedometer and swapped it in. I'm not sure if the California truck would have it's own wiring harness or not. If the event that you did have a California truck (with Cali speedometer), then you probably have a real issue behind the light.

In any case, it sounds like you are in Canada and most likely have a Canada (emissions) truck. You can determine the emissions by looking at the labels on the bottom side of the hood.

If you think it's running rich, I doubt that would be a problem with the injectors as they usually clog and restrict flow. It's probably a good idea to have them cleaned anyway because they've probably never been cleaned. But I don't think that is the root of your problem.

How do the plugs look? Lot's of dark soot? If so, then it probably is running rich in which case I'd definitely be zeroing in on the 02 sensor and a visual inspection on the ECM.

Also, you should check the vacuum lines - specifically the one to the fuel pressure regulator. It's not uncommon to find them cracked, disconnected, or even hooked up wrong. The ECM controls vacuum (through the solenoid) to the pressure regulator. If you're not getting vacuum to it, then it's running at a higher pressure than it should be most of the time. So this could give you a rich condition also. When you start the engine, you can just pull the vacuum hose off off the regulator and feel for vacuum. The only time the ECM cuts vacuum to it is when the you are under a high power condition and occasionally when the engine is hot and the ambient temp is hot. Otherwise, it should have vacuum - as long as the engine is running.

I would also check the coolant temp sensor and the air temp sensor and make sure they are within spec. They can also fool the engine into thinking that's it's cooler than it really is... also causing a rich condition.

Yea it's a Canada Emissions truck. When I took the old plugs out they were sooty yes. The coolant temp sensor I replaced not too long ago and I haven't looked at the air temp sensor. I'll start looking into the vacuum lines and probably replace o2 sensor just because and check out the ECM. Thanks for all the input.

First of all the check engine light on your truck is only a mileage driven interval for timing belt replacement. So you aren't going to be able to get it to flash. That is OBDII which you don't have. What you need to do to pull your codes is go back to the diagram and look at it. You need to bridge connection 1 and 2 with an LED test lamp and then ground your green connector. The LED test lamp should then start blinking the morse code you are looking for. Since you haven't indicated you have done that, then I don't think starting another thread, or anything else for that matter, is going to help until it has been.

Actually in my first message I did indicate that I did do that according to the link I provided. No need to go in all bold and and claim I didn't indicate that and continue to tell me information I already provided. Maybe you just don't know how to read and need to go back to grade school. And since my check engine light is now out I started a new thread under engine performance about poor gas mileage as this one is about my check engine light. I figured I might get more specific info if I did that. Pretty sure that's not against the rules.

Actually I did read your post pretty carefully. . .carefully enough to understand to recognize that maybe you don't understand that the light in your dashboard is not a check engine light. It is a timing belt interval light only. It won't ever flash error codes.

If you used an LED test lamp, I think you still should have gotten some flashes because that breakout port is for a number of test points. It isn't clear that you used an LED test lamp and if you didn't maybe that is why it didn't flash at all. An LED test lamp isn't the same thing as a regular test lamp.

Sorry for the confusion.