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Tranny fluid leaks from wires?

Two weeks ago I had my oil changed, and the mechanic at Valvoline noticed that my tranny fluid seemed a bit low. At glance, he did not see a leak, so he topped it off. One week later, I pulled off the road & noticed a burning smell & smoke coming from under the hood of the truck (2003 Nissan Frontier, automatic). Tranny fluid had squirted all over the passenger side corner beneath the hood! My family mechanic took a look and could not find a leak either. He suggested that Valvoline may have overfilled the tranny, and when the fluid expands when hot, it would have no where else to go but to squirt out the dipstick. Sounded reasonable, and didn’t cost a penny. However, one day later, the same thing happened… smoke under the hood & fluid all over. I took a closer look, and it didn’t seem like the fluid was coming from the dipstick. However, the fluid level was ok - measured both hot & cold. So I ran the engine with the hood up and took a look. The fluid appears to be dripping from a set of wires/harness plug at the corner of the passenger side. The wires are wrapped in shielding and the fluid is traveling upwards. This seems very strange, but this is where the leak is happening. Shifting is ok, doesn’t drive funny. What’s going on, and how do I fix this???

In order to get really specific you’d need to hear from some who knows this specific transmission really well - which I don’t. However, most autos have various kinds of sensors that are mounted on the case in one way or another. Speed sensors are a common one. They often thread in and out or are mounted in some other way with sealing o-rings.

If you went to a local, independently owned transmission shop (NOT a national chain operation) I’d bet someone could fix you up quickly & for not very much $$. But since the leak is apparent and the issue is external to the transmission any good local mechanic should also be able to handle it without much trouble.

DO NOT put it off and keep a very close eye on the fluid. Low fluid can create very fast transmission death.

However, most newer cars use electronically-shifted transmissions. The solenoids and sensors for these electronic controls are internally located on the valve body. This requires a sealed junction to allow the electronic wire harness to attach to the transmission case with seals to prevent transmission fluid leaks. It is very possible these seals are failing, and allowing transmission fluid to leak out just as you described.

I agree with cigroller. Find an independent transmission to look at it. A pan drop is normally all that is required to access the junction and re-seal it. If it’s been a while, a fluid change at the same time would be a very good idea.

I had this happen to me with my 2006 Chrysler, right after I got it. This is a common problem with the transmission on my vehicle, which is actually a Mercedes transmission. The fluid leaks from a bad gasket at the (maybe aptly named) NAG-1 connector. Fortunately I noticed the leak right after buying it from a small car lot, and they reimbursed me for the repair as a goodwill gesture.

I am not familiar with the transmission in your Nissan, but to repair mine was about $180 as I recall…