INOP NO SPEED, CABLE BREAK VSS HEAD SEN P/N NOISE
SUBJECT: INOPERATIVE SPEEDOMETERS
MODELS: 1989-1990 P3 MOTOR HOME CHASSIS (32) AND COMMERCIAL VAN CHASSIS (FORWARD CONTROL CHASSIS - MODEL 42)
Some of the above subject vehicles may experience inoperative speedometers. This condition can be caused by either inadequate engagement of the upper speedometer cable or a broken lower speedometer cable tip.
To correct, it is necessary to install either a new upper or lower speedometer cable. The new upper speedometer cable has a longer shaft core tip to provide full engagement of the speedometer core tip between the Vehicle Speed Sensor (VSS) and speedometer head (part of the instrument cluster). The lower speedometer cable has a metal tip replacing a plastic tip to help prevent tip breakage. Vehicle manufacturing breakpoints are listed below:
Chevrolet 1 GBJP37N7L3321236 GMC 1 GDJP32J8L3502874
Prior to performing the installation procedures verify if the condition experienced is the result of inadequate engagement of the upper speedometer cable. If an inadequate engagement condition is present, replacement of the upper speedometer cable is required. Inspect the lower speedometer cable for a broken tip at the speed sender generator. If broken, replacement of the lower speedometer cable is required.
INSTALLATION INSTRUCTIONS
UPPER SPEEDOMETER CABLE REMOVAL AND REPLACEMENT (see Figure 1):
1. Disconnect the negative battery connection.
2. Set park brake and put transmission lever in park.
3. Disconnect and remove the upper speedometer cable from the speedometer head in the instrument cluster.
4. On Commercial vehicles, disconnect the opposite end of the cable from the road speed sender generator located underneath the vehicle (outboard of the left hand frame rail and in back of the front axle). On Motor Homes, disconnect the opposite end of the cable located in the left hand frame rail across from the transmission.
5. Install the new upper speedometer cable into the instrument cluster and connect to speedometer head.
6. On Commercial or Motor Home vehicles, reconnect the opposite end of the cable to the vehicle speed sensor (VSS) chafing or high temperature areas. Clip at positioning cable.
7. Reconnect negative battery connection.
8. Check for proper operation of speedometer.
LOWER SPEEDOMETER CABLE REMOVAL AND REPLACEMENT (see Figure 1):
1. Disconnect the negative battery connection.
2. Inspect road speed sender generator for broken plastic speedometer cable tip. If broken, remove broken piece prior to installing new cable.
3. Disconnect the lower cable from the vehicle speed sensor (VSS).
4. Disconnect the opposite end of the cable at the transmission and remove cable.
5. Reconnect the lower speedometer case to the VSS.
6. Reconnect cable at transmission end. Route cable to avoid kinks or chafing.
7. Reconnect negative battery connection.
8. Check operation of speedometer.
SERVICE PARTS INFORMATION
Part No. Description Quantity P3 Model -------- -------------- -------- --------------------------------- 16154975 Upr. Speedo Cable Asm. 1 Commercial (42) with Gas Engines.
16154985 Upr. Speedo Cable Asm. 1 Motor Home (32) with Gas Engines.
16155035 Lwr. Speedo Cable Asm. 1 * Motorhome (32)/Commercial (42) w/ Gas Auto Trans & Power Disc Brakes
16155045 Lwr. Speedo Cable Asm. 1 * Commercial (42) with Gas Engines Manual Trans.
16155055 Lwr. Speedo Cable Asm. 1 * Motorhome (32)/Commercial(42) w/ Gas Engines & Auto Trans & Hydraul Brakes
*P/N 16154975 Use with RPO's LB4/L05/Ll9. P/N 16154985 Use with RPO L19. P/N 16155035 Use with RPO's LB4/L05/LI9 and M4C and JB7/JB8. P/N 16155045 Use with RPO's LB4/L05 and M20. P/N 16155055 Use with RPO's L05/Ll9 and M40 and JF9.
RPO CODES:
LB4=4.3L Gas Eng. M40=3-Spd. Auto. Trans. L05=5.7L Gas Eng. JB7=Power Disc. Drum 8,400 Lbs. L19=7.4L Gas Eng. JB8=Power Disc, Drum 10,000 Lbs. M20=4-Spd. Man. Trans. JF9=Hyd. Brake, 4 Wheel Disc
MODEL CODES:
32=Motor Home Chassis 42=Commercial-Forward Control Chassis
Parts are currently available from GMSPO.
WARRANTY INFORMATION
For vehicles repaired under warranty use:
Labor Labor Operation Description Time --------- ------------------------ ---------- N4382 R & R Upper Speedometer 0.2 hr. Cable N4383 R & R Lower Speedometer 0.2 hr. Cable
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
