Sudden decrease in FICO scoring

[Anonymous]

My FICO score was going high even though I had serious delinquencies before. I have bought a new car and I was added as co-applicant. My wife was the primary applicant and her credit history has been good. Since then my FICO score started going down. The following is the reason for decline in the score which I do not understand.

Please help me in understanding this and what should I do to avoid further decline.

The proportion of loan balances to loan amounts being reported on your installment accounts is too high

[Anonymous]

When you initially open a loan account it can cause the FICO to go down.  As time passes and more is paid on the loan baance,you will see the score increase.  Same thing happened to me when I paid my Car off.  lol.  Then loan as no longer reporting open so the only thing I had left were some deferrred student loans which still showed a high balance