Diagnostic Aids
DTC 28 will set if PCM detects one of 2 illegal combinations. See TRANS. RANGE PRESSURE SWITCH COMBINATIONS table. Check all wiring connectors for proper terminal tension. For current DTC 28, range signal will default to D4 while A/B/C range values continue to read actual trans. range pressure switch output for each range selection.
TRANSMISSION RANGE PRESSURE SWITCH COMBINATIONS (4L60-E)
| Application |
A |
B |
C |
| Park |
Off |
On |
Off |
| Reverse |
On |
On |
Off |
| Neutral |
Off |
On |
Off |
| 4th |
Off |
On |
On |
| 3rd |
Off |
Off |
On |
| 2nd |
Off |
Off |
Off |
| 1st |
On |
Off |
Off |
| Illegal |
On |
Off |
On |
| Illegal |
On |
On |
On |
TRANSMISSION RANGE PRESSURE SWITCH COMBINATIONS (4L80-E)
| Application |
A |
B |
C |
| Park |
On |
Off |
On |
| Reverse |
Off |
Off |
On |
| Neutral |
On |
Off |
On |
| 4th |
On |
Off |
Off |
| 3rd |
On |
On |
Off |
| 2nd |
On |
On |
On |
| 1st |
Off |
On |
On |
| Illegal |
Off |
On |
Off |
| Illegal |
Off |
Off |
Off |