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Discussion Starter #1 (Edited)
2005 Crew Cab 4x4 3.5

As the title says, I am having random Electrical issues.

I first started noticing my HVAC fan speed would speed up under slight acceleration. I could not understand the connection between the throttle and the fan. It is NOT related to engine speed. I can drop the truck out of overdrive and the fan speed stays constant even though the engine speed jumped.

I also would notice w heavy acceleration, sometimes the fan would turn OFF, I would get the BAT light and the airbag warning.

Once letting off the accelerator, the fan would come back on and the warning lights would go away.

The problem only seems to happen after driving a while and more often on hotter days. I do not have the issue on my drive to work in the AM, but it frequently happens on the hot afternoon commute home.

Found this thread: Weird electrical problems, airbag, lights blower motor....

His scenario is similar to mine.

My battery is a few months old. I have had the alternator tested on the vehicle by AZ and Advance Auto. They both said it was OK. I have also checked the battery connections, alternator connection and the grounds on the engine block.

My OBD2 Bluetooth scanner show the system voltage around 12.6 and ramping UP as I press the accelerator. I have seen it get as high as 18 volts. That is the scenario when the HVAC Fan turns off and the warning lights come on.

I think I will remove the alternator and have it tested off the truck.

I also just read a few threads on the splice packs. I will look into them to see if anything strange. For a 2005, my underhood is very clean and no corrosion issues, so I'm not expecting anything from the splice packs.

If anyone else has seen similar issues and has any suggestions, please help.

Thanks,. Ken
 

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Ken,
I think you will find that cleaning both “ground packs”. Be sure to scrape both sides of your electrical wires. Check for loose terminals and or broken terminals.
You may need to get someone who is more knowledgeable then me, I believe that under full throttle acceleration, your A/C is designed to cut out. Or turn off. The fan speed function has a plastic connector just inboard of your glove box. It has had a history of burning and bad connections. There is a repair kit you can purchase on eBay.
 

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Discussion Starter #4 (Edited)
Ok, update for today's drive home.

It was in the low 90's here today. The AC fan started fluctuating w the throttle w in a couple miles. I monitored the trucks voltage w my BT OBD2 Adapter during my drive home.

Idle or steady speed cruising, I was at 12.8 volts. Acceleration caused the voltage and fan speed to steadily increase to 16 volts, at which I guess there is some sort of safety that shuts off that portion of the power system. The radio would turn off, HVAC fan off, BAT light on, and the air bag warning on.

The more I drove, the worse it would get. I basically could not pull away from a stop w out the fan turning off and such.

When I got home, I left my truck running, grabbed a 10mm socket and tightened the 2 ground splice points and the ground wire behind the battery to the inner fender.

After doing that, the voltage variation and the fan speed fluctuations seemed to go away.

I did not remove the 3 bolts, they were all clean and free of dirt/corrosion. I tightened them until I got a little movement. Normally, I would not have tightened a small bolt/screw that much.

I will test this out on tomorrow's commute and report back this weekend.

Glad I found the post about the ground splice points as I think this might have fixed this problem... Of the past 3 months.
 

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Discussion Starter #5
Just to clarify, the AC fan stopping was not full throttle acceleration. It was only 1/3 throttle or so and it was the fan for the passenger compartment.

When I would lose partial power and get the warning lights, the truck engine was running normal.

I could not connect the various "unrelated" items... Throttle, HVAC fan speed, air bag, radio....

Rebuilt alternator around here is $200. Really did not want to experiment w replacement $200 parts.

If symptoms are still gone this weekend, I will open up the splice points and make sure they are all clean and tight. Today was a long hot day at work, and now raining... Not the time to play any more.
 

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Discussion Starter #6 (Edited)
Tightening those 3 grounds under the hood DID NOT fix my problem. It seemed better, but Friday was cooler out. I was nearly home before I noticed the problem starting.

I am checking the grounds inside the passenger compartment today along w cleaning the carpet really good.

Maybe once the alternator gets heated, something is breaking down inside it... I hate electrical Gremlins.
 

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I think you need to focus on the splice packs. Open up the little black plastic boxes and see what that looks like inside. There's usually corrosion between the wires and the metal contacts inside. I cut the splice packs off and put ring terminals on end of the wires and bolted them to the fender and have seen a lot of little annoying problems go away. I'm convinced that all of the blower motor problems that people have had is a symptom of the ground splice problem. I'm quite confident that this is the source of your troubles too. Tightening the mounting for these splice packs seems to have helped a little, I bet you "wiggled" stuff around a little and got a little improvement, but I think the problems are inside the little box.
Good luck, and please open those things up before buying any parts.
 

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Discussion Starter #8 (Edited)
I opened the splice packs yesterday. Wasn't too easy to get opened. But, finally figured it out. No corrosion or oxidation. Looked "like new" in my opinion.

I sprayed it w electrical contact cleaner and reassembled it w some dielectric grease to keep any future moisture out.

Test drove the truck, and still same problem.

I drove a while and turned off the AC since the weather is really nice here. A few minutes after turning off the AC, the voltage as reported on my OBD2 scanner settled out. The voltage did not fluctuate w throttle position.

Prior to that, the voltage was consistently going over 16 volts and causing the dash lights to come on and the fan shutting off whenever I applied moderate throttle.

So, seems to be caused by the fan somehow. But, the voltage fluctuations only occurs during acceleration.

Not really sure where to go from here.
 

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I opened the splice packs yesterday. Wasn't too easy to get opened. But, finally figured it out. No corrosion or oxidation. Looked "like new" in my opinion.

I sprayed it w electrical contact cleaner and reassembled it w some dielectric grease to keep any future moisture out.

Test drove the truck, and still same problem.

I drove a while and turned off the AC since the weather is really nice here. A few minutes after turning off the AC, the voltage as reported on my OBD2 scanner settled out. The voltage did not fluctuate w throttle position.

Prior to that, the voltage was consistently going over 16 volts and causing the dash lights to come on and the fan shutting off whenever I applied moderate throttle.

So, seems to be caused by the fan somehow. But, the voltage fluctuations only occurs during acceleration.

Not really sure where to go from here.
It looks like we are having nearly identical problems. I am going to remove my splice packs this week and see what happens. I've already put a new alternator in and it did not fix my problem. I created a new post earlier today and was pointed to your similar issue. I haven't noticed if the issue happens with the A.C. Off, but I think it still happens.
 

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Discussion Starter #10
I wonder if the ground wire for the fan runs through one of the 2 big multi wire connections on the passenger side of the firewall.

Maybe that specific connection is not tight enough and causing some Resistance. Resistance in a ckt can cause heat, which can cause higher resistance and a circular situation... It takes some time for the heat to build up, so maybe that is why the weird stuff doesn't happen immediately. Might also explain why it took a few minutes after turning off the fan before my voltage started to settle out and not change w engine load.

Hopefully between the two of us, we can figure out what is going on.
 

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Discussion Starter #11 (Edited)
On my drive to work this morning, I had the fan for the AC on 1 since it was not warm out at all. The weird electrical stuff started happening after about 15 minutes. I turned off the AC but left the fan on 1 to see what would happen.

The weird voltage problem went away after a few minutes. So, even though the main thing I notice is the changing in fan speed w engine load, the problem seems to NOT originate from the fan circuit.

It looks like the AC compressor is using Groung G103.

That ground is one of 3 all together on the driver's side of the block. I think I have only cleaned/checked the tightness of 2 ground wires in that location.

W the 4x4 parts, steering, engine mount etc all there, it is hard to see in that area, harder to reach anything. But, I think G103 looks promising.

G103 is the ground point for all 5 Ignition Coils !!! That should link the problem to engine load. W more engine load, the coils need more juice.

Now, to find the time to locate that wire and ground point.
 

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On my drive to work this morning, I had the fan for the AC on 1 since it was not warm out at all. The weird electrical stuff started happening after about 15 minutes. I turned off the AC but left the fan on 1 to see what would happen.

The weird voltage problem went away after a few minutes. So, even though the main thing I notice is the changing in fan speed w engine load, the problem seems to NOT originate from the fan circuit.

It looks like the AC compressor is using Groung G103.

That ground is one of 3 all together on the driver's side of the block. I think I have only cleaned/checked the tightness of 2 ground wires in that location.

W the 4x4 parts, steering, engine mount etc all there, it is hard to see in that area, harder to reach anything. But, I think G103 looks promising.

G103 is the ground point for all 5 Ignition Coils !!! That should link the problem to engine load. W more engine load, the coils need more juice.

Now, to find the time to locate that wire and ground point.
I did those grounds yesterday and it made no difference. Easiest way to get to them is crawl under truck from the front and slide in on your back.
 

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Discussion Starter #13
There are 3 grounds in addition to the one for the Neg battery cable for a total of 4.

Could be something in the wire going to that location.
 

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You can remove the kick panel on the passenger side in front of the front door and check those connections. They're for the fan wiring. Here's a video about a common problem with out trucks. You might want to check out this wiring as well:
 

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There are 3 grounds in addition to the one for the Neg battery cable for a total of 4.

Could be something in the wire going to that location.
My truck has 2 at that location. I pulled them both yesterday, took sandpaper to the ring and the mounting post. It made no difference for me. I have also replaced the ground cable from the battery to the engine block as and to the grounding point right next to the battery. Again, no change.

I previously had removed the splice packs and took sandpaper to the mounting point on the fender and the mounting ring, reconnected and it worked a little better, but then went downhill again. Last night I did it again, but this time I took apart the splice packs and took sandpaper to the connections and cleaned the crimp contacts which attaches to the wire inside the splice pack. I put it all together and so far the problems are gone. I drove it for 20-30 minutes last night and again for 20 this morning. Based upon my experience with this issue so far this would have already failed.

I ordered some crimp rings and will get some wire today and I am going to fully remove the splice packs this week some time. I suspect it is the passenger side splice pack.

So for me, I know it is not the grounds on the bottom of the block as I removed and cleaned them all.

Whatever you do don't replace the alternator as that wasn't the problem and it was expensive.

We'll get this figured out Ken.
 

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Discussion Starter #16
My truck has 2 at that location. I pulled them both yesterday, took sandpaper to the ring and the mounting post.
I thought I only has two connections there, but according to the drawings and schematic, there are 3.

I am thinking the starter, engine mount or something is hiding the third from view.

My driver's window motor failed today w window down. So that problem took my free time today.

On my drive home, I did not turn on the AC. It was in the 90's today. Last week w similar temps, the problems would have started w in a mile or two of leaving work. I had the fan on 3 all the way home. I never had the radio cut off or the dash lights coming on. When almost home, the voltage fluctuations started, but even w nearly full throttle acceleration the volts would not go much over 15. Yesterday, w ac running I could barely accelerate w out having greater than 16 volts, radio turning off and dash lights flickering.

I still think the G103 wire or connection must be the problem ckt.
 

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Discussion Starter #17
I found the third ground connection (other than battery one) on the driver's side of the engine block. It is above the "flange" right where dipstick tube goes into block.

I could not actually see it, but located it w my hands following the wiring harnesses. I merely tried to tighten it up. Too late and too tired to try and disconnect it to clean. Just know something would go wrong and I would be struggling all night getting it running for work.

I am not sure if I will be adequately able to get anything to scrub down the block to clean that.spot.
 

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I honestly think that at least 90% of all electrical problems are the splice packs. If you don't think it's your splice packs, then you didn't look at them close enough. I just had to say it.
 

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I'll say that after cleaning them last night it has worked fine. My voltage went to 16V today though, but no funky lights etc. I've ordered some crimp rings and will replace passenger side tomorrow. Driver side will follow soon.
 
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