Why do my wipers on my 1998 chevy lumina only work non hig

Do you know how to do electrical testing ? Here is diagnostic trouble flow chart .You will need a wiring diagram . Go to http://www.bbbind.com/free_tsb.html free wiring diagrams . You can see basic automotive trouble shooting videos on you tube if you are not familiar with this .
Wipers Low Mode Inoperative, High Mode Operates

2
Disconnect wiper motor connector C1.
Turn the ignition switch ON.
Set the wiper switch to LO.
Connect a test light from wiper motor connector C1, terminal B, to ground.
Is the test light on?
--
YES - Go to Step 6
NO - Go to Step 3

3
Inspect for a poor connection or an open in CKT 91.
Is a poor connection or an open present?
--
YES - Go to Step 4
NO - Go to Step 5

4
Repair the poor connection or the open in CKT 91.
Is the repair complete?
--
Go to Wiper/Washer System Check
--

5
Replace the wiper/washer switch. Refer to Multifunction Turn Signal Lever Replacement - On Vehicle in Steering Wheel and Column -Tilt.
Is the replacement complete?
--
Go to Wiper/Washer System Check
--

6
Connect a test light from wiper motor connector C1, terminal C, to ground.
Is the test light on?
--
YES - Go to Step 10
NO - Go to Step 7

7
Inspect for a poor connection or an open in CKT 95.
Is a poor connection or an open present?
--
Go to Step 9
Go to Step 8

8
Repair the poor connection or the open in CKT 95.
Is the repair complete?
--
Go to Wiper/Washer System Check
--

9
Replace the wiper/washer switch. Refer to Multifunction Turn Signal Lever Replacement - On Vehicle in Steering Wheel and Column -Tilt.
Is the replacement complete?
--
Go to Wiper/Washer System Check
--

10
Inspect for continuity between wiper motor connector C1, terminal A, and connector C2, terminal B, using a J39200.
Is continuity present?
--
Go to Step 12
Go to Step 11

11
Repair the open in CKT 196.
Is the repair complete?
--
Go to Wiper/Washer System Check
--

12
Inspect for a poor connection to the wiper motor at connector C1.
Is a poor connection present?
--
Go to Step 13
Go to Step 14

13
Repair the poor connection at wiper motor connector C1.
Is the repair complete?
--
Go to Wiper/Washer System Check
--

14
Replace the wiper motor. Refer to Windshield Wiper Motor Replacement .
Is the replacement complete?
--
Go to Wiper/Washer System Check
--