Maya,
Look at Figure 6 on page 5 of the manual. See where it says "12volt Terminal Block." (Actually it says "12 V olt Terminal B lock") It is confusing. Anyway there should be + and - markings on it. That is where you need to put the jumpers.
You can also test these connections with a volt meter when it is turned on with the ignition. This way you can tell which is positive and negative and confirm that those have power with the ignition on. Then turn off the ignition and they will probably not have power. What were they thinking when the wired this?
Let us know what you find.
