Is the Vehicle Speed Sensor a likely problem when speedometer is working?
 

Looking for advice on attempting a fix versus getting professional diagnostics.

I have a Acura 1997 CL 3.0 with a rebuilt transmission (5K miles ago) and 145K miles.

The check engine light has come on twice in two days. The first time, both the check engine light and a flashing D4 light came on. It had been running and shifting smoothly, but for some shifting was just a bit off. No speedometer issues. The weather had just turned cold. I checked the Transmission fluid - it was clear red and at the proper level (checked hot & running). Checked the ECU fuses, interior and under the hood (all good), which reset the trouble lights. Car then ran perfectly in all regards. :yum:

Next day (~10 miles later) the check engine light came on again, but no d4 flashing light. No shifting issues. No speedometer issues. Car continued running perfectly in every regard (only driven for another 7 miles since then). Error codes reported are: P1791 Vehicle Speed Sensor Failure and P0700 Transmission Control System (MIL Request). Rest the error codes.

I am looking at replacing the vehicle speed sensor and checking the TCM wiring harness myself. $45 for a new VSS - not bad.

Is doing that reasonably likely to fix the problem, or should I get a professional diagnostic to protect from some other issue? Any thoughts appreciated!

Currently the car is running and shifting smoothly. It has only been driven 2 miles since the last rest of the trouble lights, so I am waiting for the check engine light to recur. As a note, the transmission was completely rebuilt 5K miles ago with an extended 6 year 60,000 mile 100% parts and labor warranty so it should be about perfect.

Yes, I had the EXACT same issues are you`re describing.

I bought a new VSS and was going to have Big O Tires install it for me.

Turns out that it had somehow come loose and was BARELY making any contact at all.

Once they pushed it back in, all problems stopped and now she`s banging like a champ.

It`s a bit hard to find since it`s towards the back of the block so make sure that the person or you know where to find it.

Good luck!

Op and others,

The correct way to check the ATF level is...

1. Engine hot but not running.

2. After turning off the car/engine then pull the dip stick and wipe off the ATF.

3. Reinsert the dip stick and remove one more time. The fluid should be in between the marks.

Note, this the proper way to check the ATF level for both automatic transmissions... 4 and 6 cylinder engines.