When running lights or headlights are on the transmission shifts too early, causing it to bog down?

JAANTH

MEMBER
1996 FORD RANGER
3.0L
V6
4WD
AUTOMATIC
200,000 MILES

It works perfectly when the lights are off. I've gone through and cleaned up all grounding points. I have also done a computer reset.

Saturday, December 7th, 2024 AT 9:45 AM

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,323 POSTS

I would make sure the ground to the engine block and then to the chassis is good. There needs to be two grounds for the electrical system to work correctly. If this is okay, let's run a test on the alternator to see if it is changing low when the lights are on or if the alternator is throwing AC voltage, this guide can help:

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Please go over this guide and get back to us.

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Saturday, December 7th, 2024 AT 1:13 PM

JAANTH

MEMBER
2 POSTS

In between when I posted the question and you answered I started replacing the cam synchronizer, so vehicle is non op at the moment. As I mentioned in the question, all grounds have been gone through. In the cab and engine bay. The rear axle has also pooped the bed, so road tests on any fixes will be a no go for a while. My brother had this truck when the problem started, which led to replacing battery, and alternator. So, while I assume they are both okay, once I get it started up, I'll go ahead and do the charging system tests. Any other ideas? I truly appreciate any input on this!

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Saturday, December 7th, 2024 AT 3:18 PM

KEN L