2001 gmc Denali 6.0 does not have a smooth idle. Garage hooked up to computer and indicated random misfire does not have a check engine light on. Misfire/hesitation is not noticeable when accelerating only when stopped or idling. Garage sent it home saying they couldn't find anything wrong or explain why it was misfiring.

You don't say a pinout of WHAT?

https://www.google.com/search?q=pinout+diagram+E38

Denali Radio?

GMC Yukon Denali 2014 - SYSTEM WIRING DIAGRAMS

https://portal-diagnostov.com > 2020/04/13 > radio-gm...

Apr 13, 2020 - RADIO - GMC Yukon Denali 2014 - SYSTEM WIRING DIAGRAMS Dual DVD Headrest Wiring Diagram. Get Access all wiring diagrams car. Radio Wiring ...

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  All Wiring Diagrams for GMC Yukon Denali 2014

  https://portal-diagnostov.com > 2020/07/22 > all-wiring...
  
  Jul 22, 2020 - All Wiring Diagrams for GMC Yukon Denali 2014 · AIR CONDITIONING · ANTI-LOCK BRAKES · ANTI-THEFT · BODY CONTROL MODULES · COMPUTER DATA LINES.

GMC Yukon XL pinouts - PinoutGuide.com

https://pinoutguide.com > dev > GMC > Yukon+XL
Here are pinouts for GMC Yukon XL devices. ... There are 6 pinouts found for GMC Yukon XL . The pinout (pin-out) ... The pin outs diagrams are listed below.

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have you made a seperate earth for the after market unit
sometimes helps

http://stereowiringdiagram.info/2001-gmc-yukon-denali

Check on the injector pump,should have wires going to it.

should be mounted on the side of the throttle body

Hi the last digit is 0 this means its detected a fault but it does not know why the misfire is if it had 1 at end it would be sparkplug 1. and so on. 0 could mean there is a problem with the timing or there is something wrong with the coil pack , coil pack it could be a fault at the plugs or the wiring. if you remove the spark plugs and the one or 2 that don't look right, investigate them, make sure there is no problems with the case of the coil pack. color of the connections and the case cover no cracks or splits. it can also be blocked jets this can limit the fuel into the engine and cause the same fault.

Hi, there is a park relay in middle of the interior relay box under the dash to the left of the steering column. This is shown on page 6-61 of your owner's manual (http://www.extendedgmwarranty.com/owners-manual/gmc/2001-GMC-Yukon-Denali.pdf)
With the battery connected, pull out the relay and push it back in. If it clicks when you do this, the headlight switch is bad. If it doesn't click, the relay is bad. Try swapping the relay with another similar relay, such as the horn or A/C relay. If that solves the problem you need a relay. If not, you need a switch. Please let me know if you have any questions, and thanks for using FixYa.

time for a new headlight switch

Likely needs a tuneup, ie new plugs, wires, air filter, etc.

sound like sunshell in trans failed

When my check engine light went on, it was a oxygen sensor