Im working on a 2002 LW300. I believe the common theme with these codes is, all these sensors share the 5v signal from or to the ECM. Whichever it is, to or from, please correct me if I am wrong. I've been chatting with my friendly AI bot about what to do as the dredded wrench is illuminated in the control panel and she's in limp mode. I also would like a real person to chime in about my issue because I'm not convinced those bots are correct. I took my meter and checked the ohms between the ECM and the negative battery terminal and I get a reading. So I assume it's not a grounding issue robbing my voltage. But again not sure of this. I got down on the floorboard and disconnected the blue connector for sensors 1 & 2. No abnormalities there. Now if a guy were inclined he could back probe these wires, and with the key on see if my volts ramp up and down with pedal movement, right? I found a chart online that gives the expected voltage range at 0% and 100% but what wire(s)? Then at the throttle body I should have a similar situation a voltage range of something to something with key on and movement of the pedal. But again what wires would a guy probe? This then leads me to the fuel pressure sensor (P0453) on the fuel tank. My hunch is this is the root of my problem. How do I go about checking voltages at the tank? Drop the tank for the test? Or is there access to the tank from inside the car? As you can see I have no idea what I'm doing. Thanks in advance for anybody who chimes in. Have a great day!

 

Welcome, I have a twin and have had many L series cars. I have the complete factory service manual set for the 2002 L series cars.
What troubles are you having besides these codes. The wrench light indicates other non emission related issues like hard shifting.

 

The A/C doesn't work, and the temperature sensor doesn't register a temp on the gauge or my OBD deal. Nor does the fuel gauge work. The car does start and idles OK, but when you step on the accelerator pedal, nothing. It just continues to idle like before. There is more to the story, but I don't want to go down a path that isn't relevant. However, if it's truely critical and necessary I can shoot you an email with the rest of the story. I do have other throttle bodies I can throw at it, if you think that might be my issue. The car sat for 2 years before I decided it was time to do something with it and well here I am. I appreciate your time and consideration. Thank you.

 

Here is a start with the factory diagnostics. Do you have access to a scanner? If not do you have a digital voltage tester? Looks like a pedal position sensor problem not the throttle body. 2000-2002 are different from 2003-2005 pedals. Slight difference in the sweeps I think. There used to be another Saturn forum and they had a member with the manuals for a 2003, we used to compare notes on these cars.

 

This schematic pages shows where the ground and the 5v feeds are connected to the ECM. It also shows the connectors and pin locations. Have you had the ECM off of the valve cover? It grounds to the cover so everything needs to be clean and tight.

 

This also a handy site for service manuals.

 

Thank you very much. I will give it a shot after work tonight. I'll keep you posted.

 

Ultimately I changed the ECM and throttle body and now I have throttle control. But now I have antifreeze coming out that tailpipe. DoH!

 

Coolant runs through the throttle body to prevent icing. Check for coolant leaks into the intake.

 

OK, but how would that allow coolant to be introduced into the exhaust? I'm not following the logic.