2000 Chevy Impala Speedometer not functioning correctly

MIKE88216

MEMBER
2000 CHEVROLET IMPALA
6 CYL
FWD
AUTOMATIC
117,000 MILES

My fuel gauge stopped working three years ago. It picks up signal and reads correctly until the car is shaken or moved in any way, which causes it to go to the "full" mark and then when it settles down takes about 2-3 minutes of bobbing around before it reaches a stop at the correct level. I took out the fuel sending unit and checked the float and the connection to the unit and everything seemed fine. I have since been using the trip mileage to estimate my gas level and since I have just accepted and ignored it. About a week ago though my speedometer has been acting up. When I am driving for more than a half hour my speedometer starts to act up. At first the needle stays where my speed is at while slowing down but then rises when I accelerate. The needle continues to do this until it reaches the "P" (park) on the dash. I can reset the needle by parking and turning the car off and turning the key to on which decreases the speed by 5-10 mph each time I go from off to on. I replaced the vehicle speed sensor today and it is still continuing to act up. I am wondering if the dash cluster is bad but wanted to get an opinion before I go and buy it. I added the fuel gauge problem because the speedometer problem has me wondering if they are related somehow either by wiring or bad gauge cluster.

1 Reply

DAVE H

MECHANIC
13,384 POSTS

Hello .. thanks for the donation .. much appreciated

You will need a shop with a good scan tester to do the following DTC test's .. I would start with these test's and checking the wiring/connectors before replacing the cluster

INSTRUMENT PANEL CLUSTER DIAGNOSTIC SYSTEM CHECK
NOTE:Use this check as the starting point for any instrument panel cluster complaint.

Testing
Install scan tool to DLC. If scan tool powers up, go to next step. If scan tool does not power up, see SELF-DIAGNOSTICS in appropriate BODY CONTROL MODULES article.
Turn ignition switch to ON position. Attempt to establish communications with the following modules:
Body Control Module (BCM)
Electronic Brake Control Module (EBCM)
Instrument Panel Cluster (IPC)
Powertrain Control Module (PCM)
Inflatable Restraint And Sensing Diagnostic Module (SDM)
If communication is established, go to next step. If communication cannot be established, go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DATA LINE under DIAGNOSTIC TESTS
Select scan tool display DTCs function for the following control modules:
Body Control Module (BCM)
Electronic Brake Control Module (EBCM)
Instrument Panel Cluster (IPC)
Powertrain Control Module (PCM)
Standard Diagnostic Module (SDM)
If scan tool displays any DTCs, go to next step. If scan tool does not display any DTCs, perform appropriate procedure under SYMPTOM TESTS .
If scan tool does not display any DTCs beginning with "U", go to next step. If scan tool displays any DTCs beginning with "U", go to SELF-DIAGNOSTICS in appropriate BODY CONTROL MODULES article.
If scan tool does not display DTC B1000, perform appropriate procedure under SYMPTOM TESTS . If scan tool displays DTC B1000, go to DIAGNOSTIC TESTS .
Diagnostic Aids
Following conditions may result in intermittent operation of instrument panel cluster with no DTC stored:
Any condition which results in interruption of power to instrument panel cluster.
Out of range battery or ignition voltage (normal instrument panel cluster operating voltage is 9-16 volts).
Loose or damaged ground(s).
Open or shorted serial data line.
Instrument panel cluster tests for different malfunctions during different vehicle conditions. A thorough test drive may be necessary to repeat malfunction. Most intermittent problems are caused by faulty electrical connections or wiring. Check for: poor connections, backed-out terminals, dirty or corroded terminals, chafed wires, or damaged connectors.
SPEEDOMETER GAUGE &/OR ODOMETER INOPERATIVE OR INACCURATE
If instrument panel cluster diagnostic check was performed, go to next step. If instrument panel cluster diagnostic check was not performed, go to INSTRUMENT PANEL CLUSTER DIAGNOSTIC SYSTEM CHECK .
Connect scan tool to DLC. Raise vehicle sufficiently for drive wheels to rotate. Start engine and place gear selector in DRIVE. Using scan tool, monitor VSS parameter in PCM ENGINE DATA 1 data list. If VSS parameter and speedometer display agree, go to next step. If VSS parameter and speedometer display do not agree, go to step 4 .
Road test vehicle to check speedometer/odometer operation. If system operates normally, problem is intermittent. Check for poor connections or damaged wires. See WIRING DIAGRAMS . Repair or replace if necessary. If speedometer/odometer do not operate normally, go to next step.
Replace IPC. See INSTRUMENT PANEL CLUSTER (IPC) under REMOVAL & INSTALLATION then go to next step.
Road test vehicle to check speedometer/odometer operation. If system operates normally, repair is complete. If problem still exists, return to step 2 .

Hope this helps