I have a 2000 Chevy express van with a problem in the speedometer?

If the speedo isn't working, check the vehicle speed sensor. If it is good, chances are the speedo itself is bad.

The signal goes from the VSS to the VCM (vehicle control module), then out to the EBCM (electronic brake control module) Cruise control module and dash. You might need to find a shop that does electrical, this may take some pin-to -pin testing to determine where the signal is getting messed up. Does anything else strange happen when the speedo messes up?

If you cant find a shop that is willing to do the troubleshooting, you may just wind up at the dealer. SInce the ABS light is coming on it could be a problem with the EBCM

Hello .. thanks for the donation .. much appreciated

I would be looking more into the VSS rather than the ECM .. some models of the express are also fitted with a buffer for the VSS ..I would have to know the VIN # of your vehicle to check if your vehicle has one ?? let me know

Vehicle Speed Sensor (VSS)
VSS is a Permanent Magnet (PM) generator mounted in transmission or transfer case. The VSS sends a pulsing signal to the PCM/VCM or Digital Ratio Adapter Controller (DRAC), which passes the signal on to the PCM/VCM. The PCM/VCM then converts this signal into miles per hour by monitoring the time interval between pulses. PCM/VCM uses this sensor input in controlling Torque Converter Clutch (TCC) engagement, shift speed, etc.

Digital Ratio Adapter Controller (DRAC)
DRAC compensates for various axle and tire ratios by monitoring the Vehicle Speed Sensor (VSS) signal and modifying it before passing it on to the PCM/VCM and speedometer. On models equipped with a DRAC, VSS buffer is an internal part of DRAC.

You are right there is no buffer .. and as you say changeing the cluster would have no affect on transmission function !! you could check these out ..or as you say it could be the PCM but without it throwing out codes .. it's hit and miss to locatle the fault ! I would check the TPS first before replacing the PCM

Transmission Fluid Pressure (TFP) Switch (4L60-E & 4L80-E Transmission)
The TFP is actually 5 pressure switches combined into a single unit mounted on transmission valve body. The PCM/VCM supplies battery voltage on 3 separate wires to TFP. As switches are actuated in various combinations during transmission operation, PCM/VCM can detect what gear range transmission is in.
Throttle Position (TP) Sensor
TP sensor is a variable mechanical resistor connected directly to throttle shaft linkage. TP sensor has 3 wires connected to it. One is connected to a 5-volt reference voltage supply from PCM/VCM, another is connected to PCM/VCM ground and third is a signal return which is monitored by PCM/VCM. Voltage signal from TP sensor varies from closed throttle (0.5-1.0 volt) to wide open throttle (4.5-5 volts). PCM/VCM uses this signal to determine control of fuel, idle speed, spark timing and Torque Converter Clutch (TCC). A problem in TP sensor circuit may set a related diagnostic trouble code.
Transmission Fluid Temperature (TFT) Sensor (4L60-E, 4L80-E & 4T60-E Transmission)
TFT sensor is a thermistor (temperature sensitive resistor) mounted to the transmission valve body. The PCM/VCM supplies and monitors a 5-volt signal to TFT sensor. This monitored 5-volt signal is then modified by resistance of TFT sensor. When transmission fluid temperatures are low, TFT sensor resistance is high and PCM/VCM sees a high monitored voltage signal. When transmission fluid temperatures are high, TFT sensor resistance is low and PCM/VCM sees a low monitored voltage.
PCM/VCM uses TFT sensor input to control Torque Converter Clutch (TCC) application and shift quality. Sensor circuit problem should set a related diagnostic trouble code.