At 16:30 GMT, the rand traded at 14.8250 against the dollar, 0.24% weaker than its previous close.
"The markets are likely to remain somewhat cautious ahead of the (Fed meeting)," Nedbank analysts wrote in a client note.
Investors are focused on this week's Fed meeting for clues about when the U.S. central bank might rein in its easy monetary policies. The two-day meeting will start on Tuesday and a policy statement will be issued at 1800 GMT on Wednesday.
Riskier currencies, such as the rand, thrive on U.S. interest rates remaining low because they benefit from the interest rate differential that increases their appeal for carry trade.
However, worries on the recovery of the local economy is also putting pressure on the currency, analysts said.
"A warning from the (International Monetary Fund) over the rise in South Africa's debt to GDP ratio is not helping the local currency; however, there is some good news as the IMF is expected to raise South Africa's growth forecast for the current year to 3.1%," said Andre Cilliers, Currency Strategist at TreasuryONE
In fixed income, the yield on the benchmark 2030 government bond was up 4 basis points to 8.87% in the day.
Stocks on the Johannesburg Stock Exchange (JSE) fell on Tuesday, mainly pulled down by index heavyweight Naspers and Prosus whose shares slumped for the second consecutive day on increased scrutiny on Chinese technology companies by the Chinese government. Naspers, through its subsidiary Prosus, holds 29% stake in Chinese tech giant Tencent
Over the last two trading days, both the companies have lost around 14% of their market value.
The benchmark all share index was down just over 1% to end the day at 67,341 points while the blue-chip index of top 40 companies was down 1.19%.
(Reporting by Olivia Kumwenda-Mtambo and Promit MukherjeeEditing by Peter Graff and Aurora Ellis)