The Speedometer on my 2000 K3500 bounces all over the place over 50mph. Changed instrument cluster, no help. Cruise not working and ABS kicks in at low speed all the time. Speed sensor?

There is no odometer fuse . Does the speedometer work ?

If speedometer works , you need a new instrument cluster . Pinpoint Test E: The Speedometer/Odometer Is Inoperative Normal Operation Vehicle speed information is sent to the instrument cluster from the anti-lock brake system (ABS) module over the communication network.

Possible Causes
• ABS module
• Instrument cluster

What engine speed sensor ? Location ? The vehicle speed sensor signal comes from the anti-lock brake control module , to the PCM -engine control module . Speed Information to the instrument cluster comes from the PCM on the CCD serial data bus , Suggest you google Chrysler CCD data bus . Are any warning lights lit on the instrument cluster ? ABS , Check engine etc... Sorry but I suggest you take your vehicle to a qualified repair shop that has the diagnostic tools to find the problem . http://www.cnblogs.com/shangdawei/p/3570499.html

Did you have it check for DTC'S - diagnostic trouble codes ?
Speedometer
The speedometer is an analog gauge that is located in the instrument cluster. The PCM/VCM receives an analog input from the vehicle speed sensor and converts it to a digital signal containing 4,000 pulses per mile (PPM) for the instrument cluster.
The PCM/VCM sends this digital output (4,000 PPM) to the instrument cluster on a designated circuit. These pulses can be measured in Hertz (Hz) using a digital multimeter (DMM) on the AC scale. The PCM/VCM calibration is matched to the final drive and tire size of each vehicle. If the final drive or tire size is changed for any reason, the PCM/VCM must be updated in order to match the new final drive or tire size. If not, the signal will not be accurate for proper speedometer/odometer operation. An incorrect signal can affect the antilock brakes and the cruise control systems.
The speedometer system consists of the instrument cluster, vehicle speed sensor (VSS), PCM/VCM and related wiring. The VSS is a permanent magnet signal generator that sends an analog signal proportional to the propeller shaft speed to the PCM/VCM. The VSS mounts to the transmission tailshaft extension housing on 2-wheel drive (2WD) models and the transfer case output shaft housing on 4-wheel drive (4WD) models.
Repairs to the instrument cluster can only be performed by an authorized instrument cluster service center. DTC P0502 Vehicle Speed Sensor (VSS) Circuit Low Input and DTC P0503 Vehicle Speed Sensor (VSS) Circuit Intermittent in Automatic Transmission - 4L60-E
- DTC P0500 Vehicle Speed Sensor (VSS) Circuit in Engine Controls - 4.3L Important: If the instrument cluster is completely inoperative, refer to Instrument Cluster Inoperative .
Install a scan tool.
Raise the vehicles drive wheels. Refer to Lifting and Jacking the Vehicle in General Information.
Start the engine.
Place the transmission into drive for automatic transmission and third gear for manual transmission.
Compare the displayed vehicle speed on the Instrument Cluster with the monitored speed on the scan tool.
Does the vehicles speedometer and the scan tool both display 0 km/h (0 mph)? You really need a Factory scan tool or equivalent to check this . The VSS is an input to the PCM/VCM . engine computer . You can test with a DVOM - digital volt ohm meter , for signal to engine computer .
I know most people don't like hearing this , but I suggest you take it to a ASE certified repair facility .

Sounds like someone needs to do some more troubleshooting first. Changing the cluster is not a simple matter since your mileage will be different. And the cluster is on a different circuit that the ac so one should not affect the other.

There is a plastic helical gear in the transmission, where the speedometer cable attaches. Start there. Usually 2-3 bolts that hold it in, when it comes out, some fluid will escape. Check that gear for wear, and broken splines. Then follow the cable up to the cruise control module. Some cars route the speedometer cable to the cruise control transducer, then to the firewall to the instrument cluster. That transducer goes bad. Thats what happened on my 81 olds. The speedometer would bounce around at speeds less than 15 mph. I replaced that transducer and it is steady now.

Have a factory or professional scanner hooked up , check for DTC'S - diagnostic trouble code's .GM had problem with stepper motors in side the instrument cluster ,model years 2003 to 2006 . Stepper motor's control the gauge needles .
How to repair GM Instrument Cluster Speedometer Gauge Stepper

The ABS an service brake message or probably related , have it checked for code's !

might need a new fuel level sending unit...... or the gauge cluster is bad... there was a recall years back on the gauges.... the sending unit is not terribly expensive but the gauge cluster...good luck

I have a 2000 Catera that when I changed the electronic brake control module all warning lights went off, speedo and odo worked. New EBCM is $2000 Cdn I got mine used for 170. also it can be re built at modulemasters.com for $160. Not sure about the dash light tho.
Rob

I had previously replaced the failing fuel pump on my '98 K2500 when it went out entirely. I was ready to replace my 2000 K3500's fuel gauge as it was acting up.
When I started the engine, the gauge would bounce from the middle to way past full then back. It would also jump sporadically while driving on level ground.
I checked the electrical connections at the tank and made sure the frame ground strap located nearby was making good contact. Nothing changed until I removed the instrument panel and cleaned the connections on the back. The fuel gauge seems to be operating correctly now.
There are videos on YouTube that show how to remove the instrument cluster if in doubt. Mine dash has a pop-in plastic bezel followed by 4 screws to hold the cluster in place. It took about a half hour to inspect & clean the dash connection vs. $250 to replace the pump/sending unit combo. Hope this helps.

On my 96 the PSOM module went bad. That is located on the back of the instrument cluster. Mine is analog not digital. What was happening was that the PSOM (Programable Speedometer Odometer Module) would mess up and the speedometer would jump all over the place. The tranmission is electronic and the computer would adjust and shift depending on the speed reported by the speedometer. The van would **** and shake. At slower speeds it was much better. I changed the speed sensor first without success. Changed the instument cluster and all was well.