* Shifting Problems: This could be a number of things, completely unrelated to the previous repairs. Possible causes include:
* Transmission fluid: Low, dirty, or old transmission fluid is a very common cause of shifting problems. Check the fluid level and condition. A fluid and filter change might solve the problem.
* Transmission solenoids or valve body: These internal components control shifting. A faulty solenoid or problem with the valve body can cause erratic shifting. Diagnosis requires a professional scan tool to check for transmission codes.
* Torque converter: This component can fail and cause shifting issues.
* Wiring harness: Problems in the wiring harness leading to the transmission can also cause shifting problems.
* Clutch (if manual): If it's a manual transmission, the clutch might be worn or damaged.
* Brake Light Issue: This is a separate, simpler problem likely related to the bulbs themselves or the brake light switch. It's unlikely connected to the engine or transmission issues. Check the fuses first, then the switch and the bulbs themselves.
In short: The shifting problem is likely a transmission issue requiring a mechanic's diagnosis. Don't assume it's related to the engine computer or starting relay replacements. Take it to a mechanic specializing in Sprinters or transmissions for a proper diagnosis. They'll need to check for trouble codes and possibly perform a road test. The brake light issue is a much simpler fix.
