* Low/Reverse Band: This band is responsible for engaging low and reverse gears. If it's broken, slipped, or adjusted incorrectly, these will be the only gears that work.
* Internal Transmission Damage: More extensive damage inside the transmission (broken gears, worn clutches, etc.) can also lead to this symptom. This is often accompanied by other problems like loud noises, difficulty shifting, or fluid leaks.
* Shift Linkage or Cable Problems: While less likely to cause *only* low and reverse to work, a problem with the shift linkage or cable could prevent the transmission from selecting higher gears. This is easier to diagnose with a visual inspection.
* Low Transmission Fluid: While this usually leads to various shifting problems, critically low fluid *could* restrict operation to just low and reverse due to lack of lubrication and pressure.
What you should NOT do:
* Continue driving it: Driving with a damaged transmission will cause further damage and likely lead to a much more expensive repair.
What you SHOULD do:
1. Check the transmission fluid level: Make sure the fluid is at the correct level and that it's not burnt or contaminated (smells burnt or looks very dark).
2. Inspect the shift linkage/cable: Look for any obvious damage or looseness.
3. Have it towed to a mechanic: This isn't a DIY repair unless you have significant transmission repair experience. A professional mechanic can diagnose the problem accurately and provide a repair quote. Trying to fix it yourself could lead to further damage and higher costs.
Given the age of the truck, a complete transmission rebuild or replacement might be necessary. Get a couple of quotes to compare costs before proceeding.
