No Speedo or Car Won't Shift

[HeyKanter]

95Z, 75K (wife driven) A4 tranny,

Problem: the car will go in reverse every time but when you shift into Overdrive the car has no speedo also the car will not shift but if it does shift, then when you stop it will not down shift unless you shift to Neutral turn the car off then back on again, and then back to overdrive, otherwise you are stuck the last gear that the car shifted to.

I have replaced the "Speed Control Sensor" on the tranny and nothing happened, still no speedo and no automatic shifting.

Any ideas?

[Lyle A]

Well, after you sent me that message I looked in my manual and decide that there are a million things that can cause your problem. The speed sensor would be my first guess but you replaced that. I guess it's possible that the new one is faulty. Did you replace it with an AC Delco product or aftermarket? Get you PCM scanned to see if it's storing any trouble codes pertaining to the transmission. You could have sticky valves in the valve body. Or a faulty shift solenoid. I think the PCM scan is the best place to look for faults first. Also if you plan on keeping the car for a long time then you should think about a GM shop manual from www.helminc.com

[chevymania.com]

There is a black box on the drivers side of the trans with a 8 or 10 wire plug coming out the back. This box tells the ECM and the dash indicator lamps (if equipped) what gear the trans is in. If it's bad the ECM might not shift correctly. Check to make sure it's pluged in and none of the wires are damaged at the plug.

[HeyKanter]

I have looked for the 8 or 10 wire connection and i think that you are talking about a standard tranny, the local chevy guy said i need to bring the car in and let them hook up to the computer to see what it says, which brings up the next question does the 95 have OBD I or II and what aftermarket unit is the best thing to buy that will read both?

Any idea were the speed control sensor wires go to?

[lola m anderson]

i know your car is a obd1 computor, however it has a obdII, 16 pin hookup.when you buy a scan tool you have to look for this exact cable hookup with the kit to read the codes.gm only used this for like two years, some 94's and the 95's. very irritating because your gonna have to spend close to a xtra 100 bucks to get this interface cable. we got a couple of scan tools the most current is a auto xray that seems to work nice we have the one that will do all veh's, gm,chrysler,and yes fords can sometimes be found on the property. hope the info helps

[Lyle A]

Lola, does the auto Xray give you GM DTC numbers and clear stored codes?

[HeyKanter]

I got my hands on a scanner that reads OBD I & II (along with Ford, Chrysler, imports...you name it...) the scanner reads all information once you hook it up right...

Code #24 - VSS - Vehicle Speed Sensor Error ... DUH!!!

Question is that the same thing as Speed Control Sensor and if not where is the VSS located.

[Lyle A]

The VSS is located on the tailshaft of the transmission. You can't miss it, it's a cylindrical object with wires going to it. You might be thinking of the Cruise control when you say Speed Control Sensor. The cruise control also uses the VSS to control speed. What scanner did you get a hold of? Sounds like a Snap-On to me.