What are common problems with the transmission in a 1990 Cadillac Brougham?

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The 1990 Cadillac Brougham uses the THM 700R4 (4L60) automatic transmission, which has several well-documented issues that owners should be aware of:

**Most Common Transmission Problems:**

1. **Torque Converter Lock-up Issues** - The converter may fail to lock up at highway speeds, causing poor fuel economy and overheating. This is often due to faulty wiring or a bad lock-up solenoid.

2. **2-3 Shift Problems** - Many owners report harsh or delayed shifting between 2nd and 3rd gear. This is typically caused by worn governor gears or valve body issues.

3. **Throttle Valve Cable Misadjustment** - This cable controls shift timing and firmness. If improperly adjusted, it can cause early or late shifts, or even transmission damage.

4. **Overheating** - These transmissions run hot and can fail prematurely if the cooling system isn't working properly or if the vehicle is used for towing.

5. **Sun Shell Breakage** - In higher mileage units (over 100k miles), the sun shell can crack, causing complete loss of reverse and 2nd gear.

**Prevention Tips:**
- Change transmission fluid and filter every 30,000 miles
- Ensure the throttle valve cable is properly adjusted
- Install an auxiliary transmission cooler if towing
- Use only Dexron transmission fluid

The good news is that when properly maintained, these transmissions can be quite reliable. If you're considering this particular 1990 Brougham in Huntsville, I'd recommend having a transmission specialist inspect it before purchase, especially given the unknown mileage.

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Lot 13136822: 1990 Cadillac Brougham

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Lot 13136822: 1990 Cadillac Brougham

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