COULD IT BE NUETRAL SAFETY SWITCH AND HOW DO i TEST IT . Try moving the gear selector to neutral an see if then it starts . If it does ,you need a transmission range switch ,for a automatic transmission .
If it does the same in park an neutral , voltage drop test the main battery cablb an ground . How old are the battery cables ?
Starter Voltage Drop
Looking at a wiring diagram i see testing can be done at the starter relay ,or where in plugs into the fuse/relay box . Free wiring diagrams here http://www.bbbind.com/free-tsb Enter vehicle info. year , make , model an engine size. Under system click on engine ,then under subsystem click on charging system (has starting & charging under this subsystem ). Click the search button then the blue link.
Rear heat not working ? The blower motor isn't working ? No air coming from the rear vent's ? Is it just a yukon or XL or denali ? What size engine ? 4.8 , 5.3 or 6.0 l Manual or automatic climate control ? Does the blower motor work on any speed ? The front an rear heater system are seperate , have there own electrical circuits . Could have a couple of different systems ,could have a control processor or relay's an a resistor block . Do you know how to test automotive electrical circuit's using a wiring diagram and a DVOM - digital volt ohm meter ? Plus to get at the rear heater-A/C unit you would need to take the right rear trim panel off .
2003 Tahoe No Rear Heat Fix Suburban Yukon XL Repair
With a scanner that can control output
Look for TPS % data
If it shows 1 or 2 % (no fuel pedal depress)
Reset it
It must read 0 % (no fuel pedal depress)
Run the engine to check if the problem is solved.
Not easy. You can put an ammeter inline with your battery and check the amount of drain. Be aware that electronics in your vehicle will normally draw a small current when the vehicle is turned off. If drain is unusually high (significantly more than about 300 milliamps), pull fuses until the unusual drain stops, and then troubleshoot that circuit.
One of the most common causes of this type of drain is a light that didn't go off like it was supposed to (like under the hood, in the glove box, etc). Another possible cause of what appears to be a drain is a weak battery.
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I hope I can help you with your question I believe I can first and foremost if you're having trouble starting your car on cold mornings it's probably going to be a clogged fuel filter or bad fuel pump about to go out you're having symptoms as you described and then whenever you're at 55° things start to warm up and you can start your car okay the filter is so clogged up imagine that look looking like a blood vessel okay when you have a clog in it it doesn't allow the blood to flow freely feel the same way
I suggest you get one of those manuals people get nowadays to do it yourself.. My nephew use it to repair my car and it's totally repaired now. Here's the website he bought it from. www.reliable-store.com
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Odds are you have a connection problem. Stop & buy a tube of dielectric compound from an auto parts store. Apply it to the electrical connection at the lamp after you make sure there is no corrosion present.
Seems like you have already diagnosed your problem. Sounds like a bad fuel pump. But you can check the pump if you have some one to turn the key on while you care near the gas tank. You should hear it. If not Id say its probably bad.
I am not an expert in GMC 4wd systems, but your theory is logical. Try to remove the CV joint first at the transfer case and see if you still have rear wheel drive. This will be easier than opening the front axle case and removing the components. Just take out the driveshaft to the front wheels differential and you should still have rear wheel drive.
