blackandgold51
1/2 ton status
Ive Changed the Alternator recently and still the same thing
CK5
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Why Does Headlight On 1990 V1500 350 V8 Dims When Stepping On Accelerator?
- Thread starter blackandgold51
- Start date
How old is your battery? Have you cleaned your terminals and checked your battery cables and grounds?
blackandgold51
1/2 ton status
Battery is about 3 to 4 months old and for the terminals no i have cleaned them however the terminals side posts
blackandgold51
1/2 ton status
I meant i havent cleaned the terminals
Did it start after the new battery was installed?
I would look at cleaning the connections and replacing the ground cables if they look weathered.
It would be interesting to see what the voltage reading is at the battery as you rev the engine. Of course with the lights and other accessories on.
I would look at cleaning the connections and replacing the ground cables if they look weathered.
It would be interesting to see what the voltage reading is at the battery as you rev the engine. Of course with the lights and other accessories on.
blackandgold51
1/2 ton status
When i accelerate the reading goes close to the "first red number" while headlights are on
Use a meter at the battery.
blackandgold51
1/2 ton status
A voltmeter?
rampage
3/4 ton status
Unless you want to use an ammeter with a small value (and HUGE wattage) resistor.
Maybe when you accelerate you're going faster than the speed of light.
blackandgold51
1/2 ton status
Very funny.Unless you want to use an ammeter with a small value (and HUGE wattage) resistor.
Maybe when you accelerate you're going faster than the speed of light.
Definitely check grounds. Resistance in the ground side will cause all sorts of issues. I actually popped a pair headlights in one of my old rides do to a voltage spike from the alternator, which was caused by bad grounds.
blackandgold51
1/2 ton status
How and wjere should i check for the grounds?
All of they negative battery cables, backside of the passenger side cylinder head should be a ground strap to the body, on the headlight wiring there should be some ground wires attached to the body, look for corrosion and rust.
blackandgold51
1/2 ton status
Thanks
Try this, assuming its an auto tranny: Put the truck in gear, foot on the brake. Make sure there is nothing in front just in case.
Watch the voltmeter, and gently give it gas.
If the meter drops, odds are you have a bad ground from the block to the frame. When you torque the motor, it will twist on the mounts and move the ground connections.
About the only other thing that would cause that would be a loose belt/week tensioner or a glazed belt. Either one would cause it to slip on the alternator pulley and slow the alternator briefly.
Watch the voltmeter, and gently give it gas.
If the meter drops, odds are you have a bad ground from the block to the frame. When you torque the motor, it will twist on the mounts and move the ground connections.
About the only other thing that would cause that would be a loose belt/week tensioner or a glazed belt. Either one would cause it to slip on the alternator pulley and slow the alternator briefly.
blackandgold51
1/2 ton status
Tried it without the headlights on the meter didnt drop but with healights on it andit droped
OK, that is a little strange, but I still see some possibilities. Three as a matter of fact.
One: gauge problem. If the gauge cluster has a ground problem, it might be backfeeding through the headlights. If so, turning them on would remove the auxiliary ground and cause the gauge to read wrong. To check that, you need to read the voltage at the battery with a voltmeter to verify that the cluster gauge is correct or not.
Two: Same basic idea, but the headlights are providing a ground path for more of the truck. If that were so, you might actually see a faint glow in the headlights at night with them switched off and the engine under a load.
Three: Very unlikely, but the alternator might not be able to supply full voltage when called upon to charge the battery and run the headlights.
That one can be spotted by leaving the headlights off and turning on a different load, such as the AC fan on high without the compressor being on so as to not put more strain on the belt.
If that is the case, then it could still be a belt problem, bad alternator, or bad alt wire connection.
One: gauge problem. If the gauge cluster has a ground problem, it might be backfeeding through the headlights. If so, turning them on would remove the auxiliary ground and cause the gauge to read wrong. To check that, you need to read the voltage at the battery with a voltmeter to verify that the cluster gauge is correct or not.
Two: Same basic idea, but the headlights are providing a ground path for more of the truck. If that were so, you might actually see a faint glow in the headlights at night with them switched off and the engine under a load.
Three: Very unlikely, but the alternator might not be able to supply full voltage when called upon to charge the battery and run the headlights.
That one can be spotted by leaving the headlights off and turning on a different load, such as the AC fan on high without the compressor being on so as to not put more strain on the belt.
If that is the case, then it could still be a belt problem, bad alternator, or bad alt wire connection.
blackandgold51
1/2 ton status
Ive put a new alternator in last week and still same problem. The Duralast Gold Alternator from Autozone. Such as with the headlights on the headlights will dim while the gauge will go down close to the "first r red number 8" along with the interior lights such as upper center console spot light and cluster gauge. However with the headlights off nothing happens
illmanners
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As Justin V said earlier, "All of they negative battery cables, backside of the passenger side cylinder head should be a ground strap to the body, on the headlight wiring there should be some ground wires attached to the body, look for corrosion and rust." Take a quick look at both the grounding straps on the head to block location, (could actually be on the either side, or both sides,) and pay special attention to the ground to the headlight wiring. Probably wouldn't hurt to run a new one in that location. Just make sure you are grounding to and from a good, clean, unpainted metal source. Typically, when I do an engine rebuild or install, I install all new ground straps and always run one or two extra ones. Bear in mind that the more options and electrical equipment a vehicle has on it, the more important ground is and sinec in most cases, external grounding is a bolt to strap situation, they are always subject to vibration; then can vibrate loose. Hope that helps..
