After disconnecting instrument cluster to replace bulbs, tach and speedometer do not register properly.

You might have to replace the speedometer cable

Removal Procedure

1. Remove the instrument cluster assembly. Refer to Instrument Cluster Replacement .
2. Unhook the speedometer cable from the heater case.
3. Remove the grommet from the bulkhead.
4. Feed the speedometer cable through the bulkhead.
5. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.

Unscrew the speedometer cable (1) from either the transfer case or the transmission. Remove the speedometer cable (1) from either the transfer case or the transmission. Remove the speedometer cable (1) from the clamp. Remove the speedometer cable (1) from the vehicle.
Instrument Cluster Replacement
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.
Disconnect the negative battery cable. Remove the hazard lamps switch by gently pulling the knob straight up. Remove the instrument cluster bezel from the instrument panel. Refer to Instrument Panel Cluster Trim Plate Bezel Replacement . Remove the 4 screws and pull the instrument cluster assembly forward from the instrument panel. Disconnect the 3 electrical connectors. Remove the speedometer cable at the speedometer head. Remove the instrument cluster assembly from the vehicle.
Remove the 5 screws (2) and the steering column upper and lower covers (1, 3).
Remove the 4 screws and the instrument cluster bezel from the vehicle.

Hi, this is a pretty common problem on these Silverado instrument clusters. We can definitely help you out with that. Click here to learn more about these Silverado instrument cluster problems: Dr Speedometer Instrument Cluster Repair Speedometer Repair Guage...

Hi, this is a pretty common problem on these Silverado instrument clusters. We can repair it for you or provide you with the parts to do it yourself. Click here to learn more about these silverado instrument cluster problems: Dr Speedometer Instrument Cluster Repair Speedometer Repair Guage...

Hi, it's possible the bulb is burned out or not making good contact with the circuit board. It should come on during the bulb check when you first turn the key on. Pull out the cluster and check the bulb. If it's good, see if you can clean the contact surfaces to get it working again. Or, move to another state where they don't worry about stupid things like a light bulb.

REMOVAL & INSTALLATION

See Figures 1, 2, 3, 4, 5 and 6

Fig. Fig. 1: To remove the instrument cluster, first remove the trim panel by removing the lower fascia panel

Fig. Fig. 2: With the lower fascia moved aside, remove the lower trim panel attaching screws ...

Fig. Fig. 3: ... as well as the upper attaching screws

Fig. Fig. 4: Then pull the entire instrument trim panel from the dash board

Fig. Fig. 5: Exploded view of the instrument cluster

Fig. Fig. 6: Rear view of the instrument cluster wire routing and connections

1. Disconnect the battery ground cable.
2. Remove the two steering column shroud-to-panel retaining screws and remove the shroud.
3. Remove the lower instrument panel trim.
4. Remove the cluster trim cover from the instrument panel by removing the eight screws.
5. Remove the four instrument cluster to panel retaining screws.
6. Position the cluster slightly away from the panel for access to the back of the cluster to disconnect the speedometer.

If there is not sufficient access to disengage the speedometer cable from the speedometer, it may be necessary to remove the speedometer cable at the transmission and pull cable through cowl, to allow room to reach the speedometer quick disconnect.

1. Disconnect the wiring harness connector from the printed circuit, and any bulb-and-socket assemblies from the wiring harness to the cluster assembly and remove the cluster assembly from the instrument panel.

To install:

1. Apply approximately 1 / 8 in. diameter ball of D7AZ-19A331-A Silicone Dielectric compound or equivalent in the drive hole of the speedometer head.
2. Position the cluster near its opening in the instrument panel.
3. Connect the wiring harness connector to the printed circuit, and any bulb-and-socket assemblies from the wiring harness to the cluster assembly.
4. Position the cluster to the instrument panel and install the four cluster to panel retaining screws.
5. Install the panel trim covers and the steering column shroud.
6. Connect the battery ground cable.
7. Check operation of all gauges, lamps and signals.

1. do the park lamps work?
2. dash lamp fuse burnt?
3. is the instrument cluster analog or digital?
4. digital clusters have been known to fail however the cluster lighting is controlled by a body computer.
5. proper diagnosis with require a scan tool that will access the body module ( computer)

You have a bad electrical cluster. Replace the cluster and your dash lights speedometer and tach should work just fine.

The speed sensor can be tested with a scanner. Only take 10 minutes, If it works then your instrument cluster took a dive. Same thing with the RPM. If the scanner sees it then the cluster is bad. Getting it diagnosed properly is your best bet. You can get the cluster rebuilt for alot less than new. modulemaster.com does them.

they use small bulbs in most Instrument Clusters, I would check & replace as required

1. Disconnect the battery cable.
2. Disconnect the speedometer cable from the speedometer head.
3. Remove the six screws retaining the instrument cluster assembly to the instrument panel and tilt the cluster forward.
4. Disconnect the wiring and the bulb sockets and remove the cluster assembly. NOTE: All individual instruments may be removed and serviced at this time. To install:
   
5. Position the cluster and connect the wiring and bulb sockets.
6. Install the instrument cluster assembly to the instrument panel with the six retaining screws.
7. Connect the speedometer cable and the battery cable.
8. Check the operation of all gauges, lights, and signals.