2004 Hyundai Sonata electrical system causes transmission p

SHJESSEE

MEMBER
2004 HYUNDAI SONATA
6 CYL
FWD
AUTOMATIC
85,000 MILES

After driving 500+ miles from SC to PA, transmission began to slip -- as if in neutral -- but only occurredwhen lights, turn signals, or brake lights engaged. This seemed like a transmission issue, but figured out that it only occurred when electrical system burdened. Is this a computer issue? Electrical issue? Alternator? Transmission? Is the car possessed? Any help is appreciated, as I anticipate a blank stare from dealer service department.

Monday, May 31st, 2010 AT 12:10 PM

2 Replies

KHLOW2008

MECHANIC
41,814 POSTS

Hi shjessee,

The symptoms seems odd but since you have an indication of what causes the problem then we might be able to narrow it down to the following.

1. Alternator. Get the charging rate tested.
2. Ground circuit. Recheck all grounf circuits.
3. PCM. This might be harder to check as diagnostic equipment might not show anything conclusive and the only way to test would be wih a substitute PCM.
4. Battery. Check the battery condition and terminals for cleanliness.

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Monday, May 31st, 2010 AT 4:04 PM

JAJAMES

MEMBER
2 POSTS

I have a 2004 sonata with a 4 cly engine. I had similar problems. It took me about a week to research but this is what fixed my problem. In the trunk of the car there is a plastic cover by the latch. Remove it carefully by prying it off. You should find a ground screw with at least 2 wires to it. Tighten screw if loose, mine was. That is what fixed the problem.

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Thursday, June 3rd, 2010 AT 7:54 PM