Greetings all……..

2001 TrailBlazer, 4.3L V6, 4x4, automatic, 200K miles

Many Problems…….

For the last several years the instrument cluster comes and goes, i.e. gas gage (& electronic \ digital readout on center overhead console) works when it wants to, sometimes it works other times it doesn’t (shows empty even though I just filled it up). I have lived with this, I assumed it was the fuel pump assembly (known part to fail) and did not want to go through pulling the tank. Occasionally it would run rough when first starting (slow to start, I assumed it was the fuel check valve located in the pump assembly) and then smooth out after it ran for a few seconds. Lately It has been running rough, therefore I jumped in a few weeks ago……

I changed plugs and wires a couple of weeks ago, it ran a little better (still has above mentioned fuel issue) but as of late it appears to be starting out in 2nd or 3rd gear, slow to get started but runs ok once up to speed.

I checked the codes (using a CarMD Reader, not the best but it is what I have), it returned the following codes:

· P0172

· P0300

· P0175

· P0452

· P0740

· P0753

· P0758

· P0785

· P1639

At this point I really don’t know where to start…….

Any help would be greatly appreciated

Thanks in advance

 

Update……

Just went out for a test drive, started out in drive, itworked as it should have. Reached atraffic light about 2 miles away, when starting from light it started in 3rdgear, I shifted into 1st gear and 1st gear worked, shiftedback into drive no problem. The problemseems intermittent, works as it should when it wants to, just like the gas gage…….

 

The gas gauge giving a false reading is caused from the sending unit going bad, which is part of the fuel pump. The problem you have with second or third gear starts sounds like the Vehicle Speed Sensor or Shift Solenoid A is not working.

 

What I would do? Change out the transmission fluid and filter, and get some Lubegard, really good stuff. I think it's the Shift Solenoid, which is in the valvebody. Then, get the gas tank down to about a quarter full, remove the three hoses to fuel pump (on top side, at rear of tank) and the small hose at the front of tank. Replace pump and the gas gauge should read correct level.

 

Update # 2………



Really bad news, Secondary Air Injection Hose feeding passenger side exhaust manifold has had a hole in it for quite some time, thereby porting hot exhaust gasses directly on \ into main wiring harness. Big time melt of the entire wire bundle and 4 WD vacuum hoses, very difficult to get at to attempt a repair. It appears that all or most of the insulation has been melted or compromised.



Here is \are the questions:

· Part # for the harness

· Where is it available, cheep…….

· If I get a replacement what is the level of difficulty, how much of the engine compartment needs to be disassembled

· How long will it take to complete

Thanks to all who have replied so far, and thanks for the future replies