Yellen warned Congress last week against a bid to crack down on currency cheats and said adding currency rules to trade deals could hobble monetary policy.

But the American Automotive Policy Council, which represents Ford Motor Co (>> Ford Motor Company), General Motors Co (>> General Motors Company) and Fiat Chrysler Automobiles  (>> Fiat Chrysler Automobiles NV), said the test it suggested for the Trans-Pacific Partnership, a trade pact that includes Japan, would not affect monetary policy.

"Experts agree that the proposal outlined would in no way impede the Federal Reserve from freely implementing flexible domestic monetary policies," Council President Matt Blunt wrote in a letter to Yellen dated March 2.

The Fed, like the Bank of Japan and other central banks, has loosened monetary policy and bought assets in a bid to boost growth, actions that can weaken currencies.

Automakers are worried about increased competition from Japanese cars under the TPP.

(Reporting by Krista Hughes; editing by Matthew Lewis)