MIL On, DTC P0503 Vehicle Speed Sensor Intermittent, Speedometer Fluctuates/Inop, Cruise Control Inop (Reposition/Replace). Cadillac DeVille 1999

Subject:

Malfunction Indicator Lamp (MIL) Illuminates, Speedometer Fluctuates/Inoperative, Cruise Control/Torque Converter Clutch Inoperative (Reposition Vehicle Speed Sensor Harness/Repair Connector or Replace Final Drive Internal Gear, Gear Retaining Ring, Case Extension and Final Drive Carrier Assembly)

Models:

1998-99 Cadillac DeVille, Eldorado, Seville

1998-99 Oldsmobile Aurora

Built Prior to January 21, 1999 (Build Year 9, Julian Date 021)

with 4.0 L or 4.6 L Engine (VINs C, Y, 9 -- RPOs L47, LD8, L37)

and Hydra-Matic 4T80-E Transaxle/Transmission (RPO MH1)

This bulletin is being revised to add an additional cause for this concern. Please discard Corporate Bulletin Number 99-07-30-015 (Section 7 -- Transmission).


(1)	Build Year (9 = 1999)
(2)	Julian Date
(3)	Shift and Line Number
(4)	Calendar Year (9 = 1999)
(5)	Model
(6)	Serial Number in Base Code 31
(7)	H = Willow Run Plant
(8)	Broadcast Code
(9)	Transmission
(10)	Transmission ID Location
(11)	Transmission VIN Possible Locations

Condition

Some owners may comment on one of the following conditions:

•	Speedometer fluctuates or is inoperative

•	Cruise Control inoperative

•	Decreased fuel economy

•	Malfunction Indicator Lamp (MIL) illuminated. The PCM will have a stored DTC code P0503 Vehicle Speed Sensor Intermittent

Cause

Important: Prior to performing any mechanical repair, it is imperative to confirm that the output speed sensor circuit is functioning normally and that the condition is not a malfunction in the speed sensor or cruise control system or wiring. Specifically, inspect the wiring harness connector at the vehicle speed sensor. The vehicle harness may be installed such that the harness exhibits excessive tension, causing a poor connection at the vehicle speed sensor.

This condition may also be caused by air gap variation between the speed sensor (130) and the differential carrier (110) due to movement of the final drive internal gear (120) relative to the transmission case. This causes wear of the bushing (124) in the case extension (134). Some affected transmissions may have a mis-machined final drive internal gear outside diameter and has a final drive internal gear retaining ring (135A) with a corner break at the thickest side. Some vehicles with the 3.11 or the 3.71 final drive ratio carrier assembly (100) may also have one or more planet pinions (103) with mis-machined gear teeth.


(6)	Transmission Case
(56)	Output Shaft Snap Ring
(100)	Final Drive Carrier
(103)	Final Drive Planet Pinion (4)
(104)	Final Drive Planet Pinion Pin (4)
(105)	Roller Needle Bearings (76)
(106)	Final Drive Pinion Steel Thrust Washers (8)
(106)	Final Drive Pinion Steel Thrust Washers (8)
(107)	Final Drive Pinion Bronze Thrust Washers (8)
(107)	Final Drive Pinion Bronze Thrust Washers (8)
(110)	Differential Carrier
(118)	Left Differential Side Gear
(119)	Differential Carrier to Final Drive Carrier Bolt
(120)	Final Drive Internal Gear
(124)	Bushing, Case Extension
(126)	Seal, Case Extension to Case
(127)	Stud, Case Extension to Case (1, 15 mm)
(128)	Bolt, Case Extension to Case (4, 13 mm)
(129)	Bolt, Case Extension to Case (1, 10 mm)
(130)	Sensor, Speed Output Assembly
(131)	Bolt, Output Speed Sensor (1)
(134)	Extension, Transmission Case
(135a)	Snap Ring
(135b)	Snap Ring

Correction

Reposition the vehicle speed sensor harness if pulled too tight and repair the vehicle speed sensor connector. If the vehicle speed sensor harness has been inspected and no concern was found, then replace the case extension (134) and install the final drive internal gear retaining ring (135B) without corner break. In some instances, the final drive internal gear (120) and the final drive carrier assembly (100) must also be replaced.

Service Information/Procedure

To repair a vehicle with a stretched wiring harness, perform the following steps:

Reposition the vehicle harness to vehicle speed sensor.
Repair the vehicle speed sensor connector. Refer to Testing for Intermittents and Poor Connections in Wiring Systems.

To repair a vehicle without a stretched wiring harness, perform the following steps:

Remove the transaxle case extension (134). Remove the differential carrier (110) and the final drive carrier (100). Remove the final drive internal gear retaining ring (135A or 135B).

Important: Do not reuse a final drive internal gear retaining ring with a corner break (135A).

After the final drive internal gear retaining ring (135B) is installed, inspect the final drive internal gear (120) for movement relative to the transmission case (6). If the final drive internal gear can be moved with moderate hand pressure relative to the case, install a new final drive internal gear, and re-inspect the case to gear fit.

Inspect the final drive carrier assembly (100) for mis-machined pinion gear teeth. The appearance of each tooth shape when viewed from the major diameter may not be uniform; some teeth may be sharp edged and some flat. Replace the carrier assembly if any teeth on any pinion are mis-shaped.
Install a new transaxle case extension seal (126).
Install a new case extension (134).

Service Parts Information

Description	Part Number
Gear, Final Drive Internal	8677862
Extension, Transaxle Case	8683544
Seal, Auto Trans Case Extension	8679017
Ring, Final Drive Internal Gear Retaining	8681080
Carrier, Final Drive 3.11 Ratio	24205234
Carrier, Final Drive 3.71 Ratio	24205233
Gasket, Bottom Pan	24209512

Parts are currently available from GMSPO.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation	Labor Time
K6399	1998-99 Aurora -- 3.4 hours
K6399	1998 Seville -- 2.8 hours
K6399	1998-99 DeVille and Eldorado -- 3.5 hours