05 trailblazer stalls when high beams turned on

[jscott]

Heard of this problem online but having trouble finding solution.

1. Trailblazer stalls when high beams turned on.
2. Turn off beams, truck restarts.
3. Drivers side turn signal wont blink but will dimly light up.
4. Drivers side low beam won't work when truck is driving but will when in park.
5. In the last 2 weeeks, have had a couple of stalls but truck restarted on same trip within 4 min of each other...one time.
6. Dash lights/speedo, etc do seem to faintly flicker but this has been happening since I bought it.

Have started to clean grounds under hood (has not worked yet) and will remove and spray relays with cleaner in fuse box tomorrow.

Any help is appreciated.

 

[mrrsm]

Welcome to GMT Nation...

First... Visit this Link... Follow @Mooseman 's Instructions on How To Download a Digital Factory Service Manual unique to your Year/Make/Model of SUV:

https://gmtnation.com/forums/threads/need-service-manuals-get-them-here.361/

Next... Consider getting some CRC Electrical Circuit Spray Solvent and pulling the Fuse Block from the Power Distribution Center. Use a Bright Flashlight and Examine the Contacts for signs of any Corrosion... Pay Particular Attention if you see any Copper Wiring Connections and fittings that have turned Green from the presence of Cupric-Oxide. The presence of Copper Oxide forces the system to DRAW MORE POWER to try to get the Electrical Pressure (Amperage )to drive through the Electron Flow of Current through the Circuits. Make sure the CRC Spray dries thoroughly before reconnecting the PDC Fuse Block.



Search your Downloaded Service Manual for the bulk of any Grounds listed in and around the Engine Compartment via their unique Alpha-Numeric of "GXXX" where the Triple X's represent the unique Ground and Bonding Strap Locations. Pay particular attention to any and all Ground or Bonding Straps that connect to the Firewall.

These are just preliminary suggestions as other Members may chime in with more pin-point places to search for Ground Connection or Light Circuit Wiring Problem... including Headlight Control Relays that may be loose on certain pins with stretched internal socket locations failing intermittently as well.

 

[jscott]

And I noticed this morning the left front turn signal indicator is FAINTLY glowing.

 

[mrrsm]

This may be a Long Shot... and I would not change this component out until others can advise on its potential to Short Out... but since it is central to the Headlight Circuit... perhaps a Bad Dash Panel Light Switch and Rheostat (Potentiometer) is the Culprit since the Dashboard Dimmer Switch is also part of that complex Electrical Component:

These images are from the link below:

https://www.cargurus.com/Cars/Discussion-c763_ds543436

 

[jscott]

All grounds on body and engine cleaned down to bare metal. Connections to fusebox from battery all cleaned. Sprayed fusebox relay and connections with cleaner and switched around any relays, etc in fusebox with same number. No effect.

Don't know if this helps but the driver turn signal flashes "normal" for a few seconds THEN starts to flash quickly as if the bulb is burned out. Bulb is new. I will check the other bulbs on the curcuit on the weekend but they seem to work.

This might be beyond my backyard mechanic ability.

 

[mrrsm]

There have been instances where the complicated Brass Contacts inside of the Ignition Switch have 'gone sideways' and caused Battery Bleed down Problems... and perhaps a Weakened Battery can be responsible for these bizarre lighting artifacts. Such problems can be investigated and discovered by measuring for any Silent Amperage Draw from short circuits somewhere in the vehicle using a Very Sensitive Amp Meter (Ammeter) to probe EACH and EVERY Fuse... One at a Time ...and using the Techniques described in this Video to "Run this problem of a Parasitic Battery Drain...."To Ground":

Please Turn your Sound Volume Down and disregard the Video Narrator's Appearance and mistakenly discount his advice ...for the wrong reasons:

And to Find and Download the PowerProbe Fuse Voltage Drop Chart...Visit THIS Link:

https://www.powerprobe.com/fuse-voltage-drop-charts/

 

[jscott]

Some success. Cleaned all the battery contacts and the lines that feed to the fuse box. Three wires in front cleaned and there was a fuse assembly straddling two of the wires that could be removed. Removed and cleaned this also. There was corrosion. Also sprayed the big electrical connector (with the pins) next to the fuse box with cleaner. Driving this morning the signal worked normally and when I put on the high beams the truck did not stall.
I still think there is an issue as the driver side headlight is dimmer than the passenger side. I will use the procedure explained in the previous post this weekend to continue the search for the gremlin (interesting car).

 

[jscott]

I noticed when I drove it today the interior fans are blowing much harder than before (they were weak.) Dont know the connection but I did move around all the relays or more power getting to then now.

 

[jscott]

More info. The left blinker blinks at almost a normal speed UNLESS you turn on the inside blowers which are now working much better...then it blinks fast like a bulb is out. And it still stalls when high beams are turned on.

 

[budwich]

:-( you might actually need to get out a meter to find out what happening since it appears to be electrical in nature.

some more simple tests... since you can cause stalling "easy", chase this problem. does it stall with either "flash to pass" or "turning on high beams"? Next, disconnect the headlight plug on both lamps (more work), then repeat test. For fun, try monitoring the system voltage during the "switch changes", notice anything?

 

[jscott]

Do you mean disconnect the "regular" headlights..left and right or both lamps (halogen) on left side?

only stalls when high beams on and it is not immediate..takes a few seconds. I can feel it struggling. And when it stalls low oil pressure warning comes on. I plan to play around with it this weekend.. Thanks for your help.

 

[Mooseman]

The low oil pressure message is normal since the RPM is too low to maintain minimum pressure. Same when it actually stalls.

Good luck in chasing this gremlin down. Definitely unusual and new territory for us here. I can't even see how the headlight circuit could even affect the engine like that except possibly the fuel pump is losing power. Maybe hook up a pressure tester and see if pressure drops when it stalls. Certainly sounds like that could be what's happening by the way you're describing it, similar when the pump relay is pulled.

 

[budwich]

disconnect the bright head light connector at each headlight.

further: you now added more info about the "stalls when switching on the headlights"... one: it is not immediate... you need to ensure that your observations are very good otherwise the forum will be chasing all over the place.

still further: the "stall" is only at idle not when going down the road with speed.... right?
IF so, you have an idle issue, clean your throttle body. what is your idle rpm (as read by the pcm)?

 

[mrrsm]

Two additional considerations may also be at play concerning the "Urge To Stall" that might involve your Alternator NOT being able to keep up with how it literally needs to "Refill The Battery" with Fresh Juice... On the Fly... as the Alternator does NOT serve as "The Source of the Nile" for that Juice to keep all of the Electrical Systems running.

Rather, it is The Lead-(H2S04) Sulfuric Acid Battery that performs this task... and all that the Alternator does... is to constantly try to "Refill the Juice Bucket" while the Engine is running and additional Vehicle sub-systems try to draw down that Energy to "quench their thirst" for 12 Volts of Direct Current. Testing the Alternator may reveal a Weak Rectifier as the problem. If it proves out that these two components are coupled by having a Weak Alternator AND a Marginal Battery... then this Mystery might finally be resolved.

 

[jscott]

New info. Truck will stall when high beams turned on both in park and at speed. Turn them off and truck restarts. AND I removed the left high beam fuse #5 and truck would not even start. put it back in..truck started. And removed left high beam bulb. some browning on bulb but it still lights up. when the bulb is removed..truck will not start. Any ideas what to check next?

 

[mrrsm]

Follow the line of this VOP's Investigation and PULL OUT THE HEADLIGHT RELAY. Inspect it for signs of Bubbled Plastic from Over-Heating and replace it with a Quality Relay. They are Pricey... but obviously very necessary...and other than a visit to a GM Dealership ... NAPA is the place to call first. The video explains what to do and why it is worth doing..and it appears that THIS is about as close to your symptoms with headlight problems will get...without mentioning the Engine Cut Off problems:

 

[budwich]

well the "new info" is somewhat interesting / unusual but... so you have a "new direction" which might be easier to track. Since you indicate that the truck won't start, look at the electrical conditions associated with no start (of course, are you saying "no start as in no starter attempt" or "no start, but engine turns over") Anyways, the things to check are associated with the fuel pump relay and PCM condition signals / conditions. As posted by mrrsm, check the headlight relay as a potential "quick first look".

Further, you say "when the bulb is removed..truck will not start." is this with "no high beam selected" or just a "regular start attempt" ie. nothing changed from normal day to day operation? Again strange.

One last question, what's the history of the truck and what might have been worked on that maybe "kicked this problem into gear". Ignition switch change? fuse box work?

 

[jscott]

K. I switched the relay out with the fan relay and the problem is still there. Both look fine. no bubbling, etc. I will still buy one tomorrow and switch it out. Maybe both are going?
An idea. If this does not work the only place where lights and control to accelerator are near each other is at the steering column...cruise control and brights on the same lever.

Truck will turn over but not start under "regular start attempt" when high beam fuse or headlight bulb is removed. High beam not on. The issue started about 2 weeks ago when I changed the turn signal bulb b/c the turn signal indicator was flashing fast and changing the bulb did not fix the problem. Noticed high beam issue later but do not drive truck much at night so may not have noticed it right away.
No work done except I had the muffler replaced recently.

 

[Mooseman]

Sounds like the high beam circuit is backfeeding either power to the PCM or fuel pump? Maybe pull the high beam fuse and use a multi-meter capable of measuring current draw through that fuse port with the engine running. With the HB's off, it should be 0.

Maybe time to pull the fuse box out and inspect the wiring under there.

 

[jscott]

I am officially thanking all of you for your help. Thank you.

I agree. It is like the high beam circuit is picking up a load.. maybe for the fuel pump. I will check that wiring tomorrow. I think the fuel pump relay 41 shares a ground with the lights. I will check the fuel pump ground G305. Have not checked that one yet.

Unfortunately, I cannot check the current draw as when I pull the high beam fuse the engine stalls.

 

[Bow_Tied]

Crazy problem! I feel your pain. It kind of sounds like the truck has found a ground through the headlights. If you turns the brights on and right away turn them off does it still stall? Are the lights ever on when the switch is off? Good luck on this fix. The usual approach is to keep isolating things until the problem is contained and then you drill down in the isolated area. I am not sure how to tell you to isolate this.

 

[jscott]

New info.
1. If I unhook the low beam bulb. high beam bulb does not light and turning on high beams does not stall truck.
2. Unhook high beam bulb and truck does not start.
3. Unhook headlight assembly and everything works fine.
checked all grounds and relays..all good.

Is there any kind of circuit board in the headlight assembly?
OR maybe it could be the at the steering column...the headlight switch arm assembly...which also has the cruise control on it.

 

[Blckshdw]

Is there any kind of circuit board in the headlight assembly?

No boards inside the headlight. Only thing in there that could be problematic, is the wiring in the 4 pin connector, if the insulation melted causing a short of some kind between the 2 circuits. Here's a pic I took years ago when I dismantled a set of headlights. (low beam wires were removed)

 

[jscott]

So. I am having trouble finding ground 103. Wiring diagram says "on left side of radiator support" which I did not find and on other diagrams it is above the right wheel well...which I found and cleaned.

Anyway. looks like I may try to replace the turn signal/cruise/high beams armature assembly at the steering colum. Otherwise it may be a short in a wire...which I have not found.

 

[mrrsm]

Please... Remember to Disconnect the Negative (-) Battery Cable before beginning...

Also... Since GM does not waste money on developing secondary systems technology specific to any one Truck or Car Line Series... this Article on Troubleshooting the Low-High Beam Headlight Dimmer Switch may still prove useful to you:

https://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/headlight-dimmer-switch-test-1

 

[jscott]

yep. dont want a broken nose from the airbag.

 

[Blckshdw]

3. Unhook headlight assembly and everything works fine.

I may try to replace the turn signal/cruise/high beams armature assembly at the steering colum.

When you unplugged the headlight, was it one, or both headlights? If everything functioned the way it should when they were disconnected, I would lean towards the steering column components not being the issue. At least not yet...

I would try the same process with one headlight plugged in, and then the other. See if one of them causes the issue without the other, or if the problem only occurs when both are connected. If the problem seems to happen with one side connected, swap the headlights to the other side. See if the problem follows... Much simpler to replace a headlight assembly, than tearing open the steering column

 

[jscott]

only unplugged the drivers side. The passenger has no issues...such as the driver turn signal blinks fast when turned on even tho the bulb was replaced and all headlight bulbs are dimmer on the drivers side. It is the stalling when the hign beams are turned on that stumps me and the truck restarts on its own when i turn off the high beams...both at speed and when idling.

 

[budwich]

you are continuing to "swirl"... from your recent post, you know how to cause the "no start, truck turn over condition" and can readily reproduce it.... BUT you haven't found what the reason is for the condition... does the fuel pump relay operate, does voltage get to the pump, does the pump run, etc... Now you are looking at the steering column / stalk. The stalk operation happens the same whether your lights are connected or not and therefore it is not likely the cause of the stalling (although it maybe the cause for your signal light issues which that is even doubtful). The stalk "communicates" with the BCM which then operates relays appropriately, and those relays operate the same whether there is a bulb connected or not. You need to get a meter out and find out what the electrical conditions at the fusebox, headlights, and the relays along with what is happening during your "no start, engine turning over" condition to track down the issue.

Further what fuse numbers are you referring in your "work", what engine? and I guess it is important... what year... as in when in 2005?

 

[jscott]

We did check the connections at headligth/ fusebox/relays and all were good. Just found another way to stall the truck under speed. Turn on the fog lights. It does not immediatly stall like turning in the high beams but within about two minutes the truck will stall but time length is random. Turn them off and the truck restarts on its own at speed. My friend thinks it is a backfeed problem with the grounds or a shorted wire.

 

[budwich]

well your "check the connections at headligth/ fusebox/relays and all were good." doesn't provide much detail and further a truck doesn't just stall / no start for no reason. Unless you provide the details of the electrical measurements during the "no start", you are going to be chasing the "wind". Good luck.

 

[TollKeeper]

To me, the problems he is having while the truck is running, sounds like a amperage issue at either the battery, or more likely the alternator. The alternator may have the volt output, but not the amperage output needed. This similar problem happened to me on a Pontiac Grand Am I has some years ago, and the alternator was the problem.

 

[Mooseman]

One way to check for that would be to turn on something with a high current draw, like the rear defrost, but he has indicated other symptoms that don't jive with that, like not running with headlight bulb pulled.

I'm still leaning towards a backfeed issue.

 

[jscott]

Well. Thanks for all the help but it was beyond me. Took it in to a trusted garage. Here is the result.

They found an 8V drop on ground wire on left headlight assembly.
They built new ground (separate wire) but still had stalling issues.
They cleaned buildup from throttle bore and reset idle.

Works good now.

I guess they just regrounded the headlight assembly and i do not know how to clean out the throttle assembly. I was thinking of trying something like that but it is getting cold in canada and i do not have a heated garage...And I do not like fooling around with electrical.

Cost $500 canadian ....$400 US

Jon

 

[Mooseman]

Thanks for coming back and updating us on this unusual issue.

 

[Petnatcar]

2005 4.2 TRAILBLAZER
Not sure if the electrical problem has been solved but here's what I did to fix the following:
1 - The LEFT HEADLIGHT was always dim
2 - The LEFT SIGNAL LIGHT WARNING LIGHT in the gauge cluster would be dim when I started the truck but then go out after a few miles.
3 - The ENGINE QUITS when I turn on the high beams or use the Left Turn Signal.
4 - The LEFT REAR SIGNAL LIGHT and the RUNNING LIGHT were both partially lit all the time.

What I did to solve the problem:
1 - CLEAN EVEY GROUND CONNECTION you can find especially the two battery straps on the side of the engine block.
2 - Running a dedicated ground wire from the headlight ground wire to the chassis made the headlight brighter.
3 - Replacing the Signal Light Flasher Module under the dash solved the Turn Signal problem.
4 - Replacing the HEADLIGHT SWITCH did nothing.

NOW EVERYTHING IS WORKING AGAIN for the time being.

 

[mrrsm]

Nicely Done! Post#5 in THIS Thread covers the relationship issues with Shared Grounds between the Left Headlight, The Left Turn Signal and The Fuel Pump Relay at the G-107 Position on the Engine Block:

Electrical Ground locations

While troubleshooting a bad ground I came across some scans of the service manual regarding electrical ground locations for our platform posted on another site. This includes both short and long wheel base, as well as both 4.2L and 5.3L. Credit goes to Wex...

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