20 Most Recent 2005 GMC Sierra 2500HD 4WD Questions & Answers


The extra battery is there because of the glow plugs and intake heater of the duramax. During cold weather both of these systems draw high amperage from the batteries. A single battery will function, but not as well as a pair.

2005 GMC Sierra... | Answered on May 12, 2017


the maximum pay load is 3534 lbs (3.5 tons ) and the maximum towing capacity is 18000 lbs or 9 tons
from your description of 2 thermostats I take it is a v8 hopefully a 6.6 ltr v8 turbo diesel
it should have come with a 6 speed allison auto transmission.
with a 35ft, 5th wheeler behind it the combined gross max mass would be getting close to max allowed
add any speed on the highway and the transmission will be running at high oil temperatures and that heat is transferred to the radiator by the transmission oil cooler in a tank of the radiator
the high oil temps could be slippage in bands and clutch packs in the transmission( not noticeable under normal driving conditions) so an check and adjustment would not go astray
next if the adjustments are set properly, it may become necessary for you to consider an air to air transmission cooler so that the heat from the transmission is transferred to passing air flow and not accumulated and added to engine coolant temperature
those kits are available from most accredited transmission specialist shops and will reduce the transmission oil temp by at least 40%
taking that the coolant temp is 95 -98 c the transmission oil will be running a lot lower, saves the oil and the transmission and will help prevent boiling of the coolant
it may be necessary for you to lock up the fan clutch as well

2005 GMC Sierra... | Answered on Apr 06, 2017


It's part of the RAP (Retained Accessory Power) circuit. Yours may be actuated by a pin switch on the hinge side of the door jamb or inside the door as actuated by the door handle linkage.

Thread radio stays on when door is opened

2005 GMC Sierra... | Answered on Nov 09, 2015


May be blockage in the system caused by either Dirt or heavy build up of carbon in system but more likely the filter is doing its job and his becoming blocked.
Change the oil when it is HOT and the filter and you should be OK

2005 GMC Sierra... | Answered on Aug 03, 2015


check for power/ground at the blower motor if you have this replace the motor. if not you will have to check the wiring back from the motor to the switch.

2005 GMC Sierra... | Answered on Jun 24, 2015


That transmission is a 4L80E a pretty hefty transmission.The reverse band is probably slipping or broken,or you may have some broken hard parts either way the transmission needs to come apart comepletly.

2005 GMC Sierra... | Answered on Mar 08, 2015


sounds like you have checked a lot of things if it was mine I would do new intake gaskets, I had a 2002 Sonoma I did a lot of what you did and every time I gave it back to owner a few days later lite was on and p0300 I did intake gaskets and its been good 2 yrs now,not sure what gaskets you got but gm use plastic ones I got new gm ones and they were aluminum type call gm dealer parts good luck

2005 GMC Sierra... | Answered on Mar 05, 2015


Could be a bad ignition control module or a compression issue as well. A methodical diagnosis needs to be performed so you don't keep chasing your tail and spending tons of time and money on this issue. Looking up a factory manual that covers your specific vehicle and testing operation of all suspect systems would be my next move. Misfire under load isyour symptom, the cause can be mechanical or electrical.

2005 GMC Sierra... | Answered on Mar 05, 2015


Owner's manual, troubleshooting? probably an electrical control problem in the differential.

2005 GMC Sierra... | Answered on Mar 04, 2015


Use tensioner release tool to loosen belt and pull it off tensioner, paying careful attention to how the belt is routed through all the pulleys.

2005 GMC Sierra... | Answered on Jan 21, 2015


maybe but have the case serviced with new fluid or do it yourself then clean the leak area and when it dries spray foot powder on the area then after a week you can see exactly where the leak is

2005 GMC Sierra... | Answered on Jan 08, 2015


just had this problem it was the PDM ended up replacing the glow plugs
best price and life time warranty for both was at Auto Zone recommend if you buy the PDM get the extension cable and move the PDM to a cooler location

2005 GMC Sierra... | Answered on Dec 16, 2014


Most likely problem is the brake light switch is broken or out of adjustment. The switch is located under the dash on the arm lever of the brake pedal. When the pedal is at rest, the arm presses the switch in and turns off the lights. If the switch gets loose, broken, or out of adjustment, it may not close and allow the lights to stay on constantly.

2005 GMC Sierra... | Answered on Aug 04, 2014

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