99 Town Car Transmission Not Unlocking Will Not Coast
Symptoms
- The transmission will not shift out of Park.
- The car will not coast when the transmission is in Neutral.
Causes
There are a few possible causes for this problem:
- Faulty shift interlock solenoid
- Faulty neutral safety switch
- Faulty transmission control module (TCM)
- Mechanical problem with the transmission
Diagnosis
To diagnose this problem, you will need to perform the following steps:
1. Check the shift interlock solenoid. The shift interlock solenoid is located on the side of the transmission. It is a small, black solenoid that has two wires connected to it. To test the shift interlock solenoid, you will need to remove the two wires from the solenoid and then use a multimeter to test the resistance between the two terminals. The resistance should be between 10 and 20 ohms. If the resistance is not between 10 and 20 ohms, then the shift interlock solenoid is faulty and will need to be replaced.
2. Check the neutral safety switch. The neutral safety switch is located on the side of the transmission. It is a small, black switch that has two wires connected to it. To test the neutral safety switch, you will need to remove the two wires from the switch and then use a multimeter to test the continuity between the two terminals. The continuity should be closed when the transmission is in Neutral and open when the transmission is in any other gear. If the continuity is not closed when the transmission is in Neutral, then the neutral safety switch is faulty and will need to be replaced.
3. Check the transmission control module (TCM). The TCM is located on the side of the transmission. It is a small, black box that has several wires connected to it. To test the TCM, you will need to use a scan tool to read the fault codes from the TCM. If the TCM has any fault codes, then it will need to be replaced.
4. Check the mechanical condition of the transmission. If the shift interlock solenoid, neutral safety switch, and TCM are all functioning properly, then the problem may be mechanical. To check the mechanical condition of the transmission, you will need to remove the transmission pan and inspect the gears and other internal components.
Repair
The repair for this problem will depend on the cause of the problem. If the shift interlock solenoid is faulty, then it will need to be replaced. If the neutral safety switch is faulty, then it will need to be replaced. If the TCM is faulty, then it will need to be replaced. If the transmission has a mechanical problem, then it will need to be rebuilt or replaced.
Cost of Repair
The cost of repair for this problem will vary depending on the cause of the problem and the cost of parts and labor in your area. However, you can expect to pay between $500 and $2,000 for the repair.
Prevention
There is no sure way to prevent this problem from occurring. However, you can reduce your risk of experiencing this problem by having your transmission serviced regularly and by avoiding driving in harsh conditions.
