4.) To diagnose a transmission with a shifting problem, a technician must first check the: A. TPS voltage. OB. fluid level. OC. engine operation. OD. control system with a scan tool.

## Step 1<br />The problem is about diagnosing a transmission with a shifting problem. The technician must first check the fluid level in the transmission. The fluid level is crucial because it can affect the transmission's performance.<br /><br />## Step 2<br />If the fluid level is low, it could indicate a leak in the transmission. This could be due to a variety of issues such as worn-out seals, damaged gaskets, or a malfunctioning valve body.<br /><br />## Step 3<br />On the other hand, if the fluid level is high, it could mean that there is an overfill condition. This could be due to a malfunctioning pressure relief valve or a malfunctioning vacuum modulator.<br /><br />## Step 4<br />Therefore, the technician must first check the fluid level to diagnose the transmission's shifting problem.