A flashing CEL (Check Engine Light) is something serious to be concerned about. A flashing CEL indicates that your vehicle's engine is misfiring, which could severely damage your catalytic converters.
Your best bet ,take it to a qualified repair shop .
Lighting control module ? ?????? Hazard / flasher module ! Now ( there''s not even an electrical signal where the fuse plugs into the interior fuse panel.) What FUSE ??????
Stop Lamps
The STOP LP 25 A fuse in the underhood fuse block supplies battery positive voltage to the normally open stop lamp switch. When the driver presses the brake pedal, the switch contacts close and battery positive voltage is supplied to both the STOP 15 A fuse and the CHMSL 10 A fuse in the I/P fuse block, and to the turn signal/hazard module. The turn signal/hazard module then supplies voltage to both of the trailer rear turn/stop lamp supply voltage circuits. The voltage from the CHMSL 10 A fuse is to the center high mounted stop lamp (CHMSL) and the trailer jumper harness. The voltage from the STOP 15 A fuse is to the stop lamps, throttle actuator control (TAC) module, and the cruise control.
Backup Lamps
The backup lamp request signal is sent from the powertrain control module (PCM) to the body control module (BCM) on the Class 2 message system. This signal is based on the park neutral position (PNP) switch signal. The BCM supplies voltage on the backup lamp supply voltage circuit to the backup lamps and to the automatic day/night mirror. Voltage for the courtesy lamp supply voltage circuit and backup lamp supply voltage circuit is from the TBC B fuse in the instrument panel fuse block directly through the BCM to these circuits. A short to ground on either of these circuits will open the fuse. The backup lamps are grounded at G401.
For trailer wiring, a separate backup lamp circuit is connected through the underhood fuse block from the TRLR B/U 10 A fuse to the trailer wiring harness.
Turn Signal/Hazard Lamps
The IGN E 10 A fuse in the underhood fuse block supplies battery positive voltage to the turn signal/hazard switch assembly. The FLASH 25 A fuse in the I/P fuse block supplies battery positive voltage to the turn signal/flasher module and ground is supplied at G200. When the turn signal switch is placed in either the left or right position, a voltage signal is completed from the turn signal switch to the turn sign/flasher module. When the hazard flasher switch is activated, a ground signal is completed from the turn signal/hazard switch to the turn sign/flasher module. The turn sign/flasher module then sends an on-off voltage signal through the LT TRLR, RT TRLR, LT TURN or RT TURN 10 A fuses in the I/P fuse block to the appropriate turn signal or to all 4 fuses for hazard operation. The instrument panel cluster (IPC) indicators receive voltage from the LT TURN and RT TURN fuses as well as the DDM/PDM for the mirror turn signals. The DDM/PDM has no function or control of the mirror turn signals other that a pass through connection for the circuits. The audio chime is also activated when the turn signals are on. When the hazard switch is pressed, all turn signal lamps will flash including both IPC turn indicators. The front turn signals are grounded at G100. The rear turn signals are grounded at G401. The Mirror turn signals are grounded by the DDM/PDM.
Do you know how to do automotive electrical circuit testing with a test light or volt meter ? How to read an use a wiring diagram to pin point testing points . ( connectors , fuse locations etc... ) How to use a power flow chart ? Here is a site for just such info .
http://www.bbbind.com/free_tsb.html Enter vehicle info . year , make , model an engine size . System click lighting , subsystem exterior lighting . Second diagram shows trailer wiring .
Electric Testing Techniques You Need to KnowMastering Voltage Drop Testing with Pete Meier and Jerry TrugliaCHEVROLET 2007 SILVERADO TRAILER LIGHT TROUBLESHOOTING
What flashing light ? Check engine ? You either have a bad engine misfire that could lead to a destroyed catalytic converter . Or a problem with Throttle Actuator Control (TAC) System. The A/C making a horrible noise , the A/C only has two moving parts the compressor an the compressor clutch coil , your compressor is locking up an you hear the serpentine belt . You'll burn up the serpentine belt . Your to vague in you posting suggest you take it to a qualified repair shop .
Do you know how to do automotive electrical testing ? Videos on youtube showing how to do it . Does your Yukon have manual or automatic Heater/AC system ? Could be the blower motor is bad , blower motor control module (if automatic ) Do you hear the blower motor running ? 2005 Chevrolet Tahoe Blower Not Working Chevy GMC same thing
problem most likely not in the diff but in the diff mounting and suspension points
a noise on acceleration or deceleration indicates that the diff housing is free to react to the load being applied and that is mounting bushes , broken mounting plates or other suspension problems
consider this to see if it fits
when you accelerate the reaction of the diff is to roll upwards as the wheels have traction but when under brakes ( deceleration ) the diff rolls forward
hence the bangs in both directions
suggest that you change mechanics and take it to a specialist shop that deals in your make of vehicle for a proper under body inspection of mounts , rubbers, pins and chassis mounting points
another issue her and that si the engine reacts the same way so check engine mounts and reaction rod bushes
Where's the clicking noise coming from ? Under the dash , under the hood in the engine compartment ? Do starter circuit voltage drop test ! When the key is in start position is there constant B+ voltage at the 10 amp crank fuse in the under hood fuse box ? This is an input to the PCM - engine computer to energize the starter relay ! Starter Voltage Drop The battery is good , starter is new ,what about the cables ? watch this video on testing starter circuit !
Throttle Body Sensor or your accelerator pedal is the cause of code P1515. Your GMC or Chevy truck gas pedal is controlled by the vehicle's computer. I know what a idiotic feature.. But replace that & clean or replace your mass airflow sensor as well... Problems resolved!!!
The Internet, though, has a large number of web sites where
you can buy service manuals and schematics from bookstores,
publishers, and other collectors. Here is just a sampling of
what sites are out there:
Factory Auto manuals
http://www.factoryautomanuals.com/
search for : factory service auto repair manuals
Repair Service Manuals
http://www.repairservicemanuals.com/
the largest collection of Automotive Repair Service Manuals
and Owners Guides on the internet. Our database currently
holds over 54,000 entries dating back from 1940 to more
recent 2011.
about Chilton Repair Manuals
http://www.chilton.cengage.com/
about Haynes Repair Manuals
Haynes Publishing
Haynes auto manuals
http://www.haynes.com/
The temperature blend door is stuck on the A/C side ! Do you hear a clicking noise behind the dash ? Has an electrical controlled actuator that switches a door inside heater - A/C box from A/C to Heat . So the blower is blowing air over the A/C evaporator core all the time , not switching !
The vanity mirror lights get power from the body control module same as map lights and rear courtesy lights among others.
You may need a wiring diagram to diagnose.
