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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29427
Experience:  GM Grand Master Technician 2007. 14 years experience.
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HEADLIGHTS GO OFF WHILE DRIVING THEN COME BACK ON; ALSO NEED

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HEADLIGHTS GO OFF WHILE DRIVING THEN COME BACK ON; ALSO NEED TO KNOW LOCATION OF CAMSHAFT POSITION SENSOR ON 99 CHEV P/U 5.7 ENGINE

GM Tech (Cam) :

Hello, I'm Cam.


 

GM Tech (Cam) :

Does tilting the column change the headlights?


 

GM Tech (Cam) :

And the cam sensor is in the base of the distributor under the rotor, 3 pin connector.


 

Customer: replied 4 years ago.

tilting steering wheel doesn't help

Ok, Is it both high and low beams?
Customer: replied 4 years ago.

Yes

Are you near the vehicle so you can do some testing as we speak?

if so, take the tilt lever out, remove the screws that hold the trim in place and then inspect the wiring at the back of the dimmer switch in the column. On these vehicles, the wiring is notorious for pulling out of the connector.
Can you check and see please?
Customer: replied 4 years ago.

all wires are connected; about 6mo ago I had no headlights so the dimmer switch was replaced; after that I never had no daytime running lights but didn't want to go days w/o my truck nor the expense of having work re-done so just did w/o. Some time after that I started with this problem. Could this be related and what else can I do at this point.

With that trim off, lets do some simple tests.
If you jump the yellow to green at the back of that dimmer switch, do the lights come on?

If no, does the yellow have power with the lights on?

There are many tests we can do with simple tools and junks of wires.
Customer: replied 4 years ago.

I am a woman so need a little more help than men, can you tell me how to pull the wire harness (without breaking) so that I can perform this test; also, I see 2 yellow wires not just one.

Ok, no problem at all.
We will not be pulling the wires, but using a knife to cut only the shielding on it.
The yellow wires, do you have one close to the light green and tan wire?
Customer: replied 4 years ago.

the 2 yellow wires are next to each other and there is a light green wire but no tan wire (after much disagreement between two of us), there is a dark and light green wire and a dark and light grey wire as well, among other colors of course. the lights do not turn on when yellow and green wires are jumped. How do I check if there is power in the yellow wire?

Use a simple test light. It will clip to the metal around the column and you can test with the probe end. Remember the lights must be on.
Customer: replied 4 years ago.

ok, used the test light with lights on and there is no power to either yellow wire

OK, at the back of the dash headlight switch, is there power to the thick red wire?
Customer: replied 4 years ago.

I figured if switch light turns on the headlights there had to be power, but at your suggestion checked anyway and there is power to thick red wire

Jump power to the thick yellow there and see what happens.
Customer: replied 4 years ago.

what exactly do I need to look for and am I jumping the power from the thick red wire to the thick yellow wire?

YEs, and you are looking for the headlights to come on and power to the yellow wire of the same thickness at the headlight dimmer switch.
Customer: replied 4 years ago.

using the thick red wire I jumped power to the yellow wire at the dimmer switch and the lights did not come on.

I meant to jump power to the thick yellow at the headlight switch and test at the dimmer switch.
Customer: replied 4 years ago.

there is no thick yellow wire at the headlight switch the only thick yellow wire


are the ones leading to the dimmer switch

The THick yellow wire is off the terminal G at the main headlight switch, the red in is terminal C.
Customer: replied 4 years ago.

there is only a thin yellow wire on terminal G; jumped power from C to G and headlights did not come on

IS there power on the yellow at the dimmer then with the power jumped between the red and yellow at the main switch?
Customer: replied 4 years ago.

what main switch??

The switch in the dash that you turn to turn the headlights on.
Customer: replied 4 years ago.

I jumped power from Terminals G and C at the headlight switch to yellow wire at the dimmer switch and headlights still do not come on

Did the yellow at the dimmer switch in the dash get power when you had terminal C jumped ot terminal G of the main headlight swtich?
Customer: replied 4 years ago.

I am jumping terminal G and C at the headlight switch with a test light and wire. The test light is "on" when I jump from terminals G and C to yellow wire in dimmer switch

Ok, perfect, now that means power is getting into the dimmer switch but not coming out, and that means the dimmer switch is faulty in the column then.
Customer: replied 4 years ago.

If that is the case why do the headlights come on at all???

Poor contacts inside the headlight dimmer switch. I would confirm by jumping power to the tan and green wires at the dimmer switch to see if the low and hig beams come on to confirm this.
Customer: replied 4 years ago.

remember there is no tan wire - there is dark grey and light grey

Then you are at the wrong spot, there are many wire to the dimmer switch in the column and a light green and a tan are 2 of them.
Customer: replied 4 years ago.

of all the wires in the column that lead to the dimmer switch there is no tan wire - there is a brown (almost rust) and an orange wire but no tan wire.


 


in 99 there was an old and new body style - I have the old body style, could there be a difference in the wiring due to this.

I have been on the old style based on the engine you provided. Try the rust colour, is it one over from the light green?
Customer: replied 4 years ago.

low nor high beams come on

Find the wiring at the base of the column switch, the large connector and jump power to the light green and tan there, pins E11 and E12.
Customer: replied 4 years ago.

so what am I looking for now? does this mean the dimmer switch may not be faulty after all?

It may not but I want to bypass that. Down further where the large connector is, jump the wires I indicated.
Customer: replied 4 years ago.

are pins e11 and e12 the same as the light green and tan wires?

yes but on the body side of the connector.
Customer: replied 4 years ago.

I don't have good access w/o removing some parts and have to go to work so no longer have time to do anything else. How much will I be charged?


 

The price is what you posted when you asked the question and you can reply later for follow up if need be on this.

Thank you for allowing me to assist you. Please rate my answer 3-5 and feel free to ask any follow up questions regarding this issue you may have.

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