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1998 Cadillac Eldorado P1810 DTC: Sporadic Gear Engagement and Diagnosis Tips

Model: 1998 Cadillac Eldorado Fault Code: P1810 Posted: 2017-06-25 08:50

I own a 1998 Cadillac Eldorado that intermittently fails to engage gears. The only Diagnostic Trouble Code (DTC) I'm receiving is P1810, with no other codes present. I've already replaced the Powertrain Control Module (PCM), and I've thoroughly inspected both the 20-pin transmission connector and the PCM connector—no bent pins or debris were found. While some sources suggest a faulty TFP (Transmission Fluid Pressure) Valve Position Switch could be the cause, are there any other potential components or wiring issues that might trigger this DTC? The issue is intermittent and frustrating, especially since I'm on a fixed income and want to avoid unnecessary transmission repair costs. I've tried starting the car multiple times with no consistent results—sometimes it moves fine, other times it won't shift at all. I'm seeking reliable, cost-effective troubleshooting steps before visiting a shop.

Related fault codes
P1810
Comments (6)
Anonymous 2017-06-25 09:53

Are there any additional DTCs present? Has the vehicle undergone recent maintenance or repairs? Is transmission fluid level normal—check the hints section for reference. Ensure that no wiring circuits in the harness are grounded (only one circuit should ground). Verify a solid 12V supply with the key off engine (KOEO). Note: A remote starter could interfere—please confirm if this vehicle has one.

Anonymous 2017-06-25 10:30

Transmission fluid level is normal and no remote start system was installed. No recent repairs or modifications have been performed. I purchased the car from California, where it had sat for about a year. The seller claimed it ran and drove normally. Upon delivery to Southern Indiana, the battery was missing. I bought a new battery at Walmart while it was being transported. After installing it, I started the car but couldn't move it—so I had to tow it off the trailer with my truck. I was frustrated and let it sit for several days. When I tried starting it again, I had to go through the learning process to get it running. It would start and drive fine one day, then fail to shift when I attempted to back out of the garage the next day. It would back up without issue but wouldn't move forward—this behavior is extremely inconsistent and driving me crazy.

Anonymous 2017-06-25 12:06

Consider inspecting the transmission harness connectors for corrosion or damage. Use a can of DEOXIT to clean connections, followed by dielectric grease to prevent moisture ingress. Water exposure could be a factor—perform a visual inspection for chafing or wear, especially given the intermittent shifting issue.

Anonymous 2017-06-25 13:06

I'll try cleaning the connectors with DEOXIT and dielectric grease first.

Anonymous 2017-06-25 15:15

No improvement after cleaning. I truly appreciate all the advice—this issue is very frustrating, especially as I'm disabled and on a fixed income. I absolutely want to avoid paying for a full transmission replacement when it may not be necessary.

Anonymous 2017-06-25 16:06

Could you please specify the location of the TFP valve position switch? The 20-pin connector is located on the driver's side, with the back end appearing to connect into the transmission. I'd like to verify if this component is accessible and whether it should be tested or replaced.