His check engine lights on with p0101,171 and 174 codes, and has horrible fuel economy. I did a search and will clean the mad and check for intake leaks. Also his speedo and tach no longer work, one went then the other a time later. I was using his scanner and it showed TP% I'm assuming throttle position and it was about 16% at idle and pressing the throttle it didn't seem to correspond with. What I figured the throttle to be and it reacted slowly. He has the electronic throttlebody so how do I reset it back to zero?

 

ETC will not read 0% at idle. PCM opens throttle to regulate idle speed. P0101 is predicted air flow error. Might want to checked for plugged cats. P0171 P0174 are B1 and B2 lean. Fuel trims are having to add more fuel than normal to run at stoich. Low O2 readings at WOT can cause them to set too. Stepper motors are a known issue with that year cluster. They are not hard to change and can be purchased cheap on ebay (search gm cluster stepper motors). Plenty of youtube videos showing how it's done. You need to have some soldering and desoldering tools and skills.

 

Thanks for that insite on the etc. wouldn't a specific O2 code pop if it was one of them? I'm hoping it's an intake leak as I can do that here before they go home. I'll have to ask him if it's bogging down or falling on its face for cat issues. I'll let him know about the cluster.

 

Actually MAF being bad could cause lean codes to show up also... If you can see it check your BARO in correlation to your MAP with engine off they should read the same! The barometric pressure sensor is built into the MAF on these trucks along with the IAT, easy way to check IAT is to (again koeo) check it against the ambient air temp sensor, or weatherbug on your phone.... Also check that the MAFgm/sec are near 0 koeo and somewhere around 5-6 at idle and increase as rpm does... All of this assuming you have a scanner you can see data on... Best way to check for leaks would be to smoke intake, with throttle body blocked... And you should have tp1/tp2 pids on your scanner that should oppose each other (ie tp1 at .5v tp2 at 4.5v) always equal to 5v 50% throttle in theory should be tp1 2.5v/tp2 2.5v, wot should be something like tp1-4.5 and tp2-.5.... Sorry had similar issue at work last week that kicked my butt til i took step back and found the lean condition was actually a severely rich condition because the truck thought it was somewhere in denver, CO when in all actuality it was 3.5 miles from the atlantic ocean about .5 foot above sea level not a mile above it...