6–102 Copyright © 1998 General Motors Corp.
WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL
Main code 61 indicates the ECU has detected a hot fluid condition in the output retarder.
Possible causes (but not all causes) for hot fluid are:
1. Prolonged retarder use.
2. Low fluid level.
3. High fluid level.
4. A retarder apply system that allows the throttle and retarder to be applied simultaneously.
5. Cooler inadequately sized for retarder.
If the validity of the hot fluid diagnosis is in question, temperature can be checked by using a temperature gauge at the
retarder-out port or by reading retarder temperature with the Pro-Link
®
diagnostic tool. Another method of checking
retarder temperature is to remove the B connector at the ECU and measure resistance (Ohms) between terminals B1
and B4. Compare the resistance value to the value in Figure 6–35 to see if result is within the expected operating range.
NOTE: Use the Pro-Link
®
diagnostic tool to determine the software version being used.
The retarder temperature sensor is located externally on the retarder housing. When retarder temperature reaches a
preset level, a retarder overtemp light is illuminated. The preset temperature for Version 6 software is 138°C
(281°F) and for Version 7 software is 141°C (285°F).
Table 6–7. Transmission Retarder Operation as a Function of Temperature
Description
Version 6*
(501 and 502)
Version 7
(D70)
Version 7A
(P01)
MD Retarder, Light On
MD Retarder, Light Off
166°C (330°F)
159°C (318°F)
141°C (285°F)
135°C (275°F)
+
166°C (330°F)
159°C (318°F)
MD Retarder, Set Hot Code (61 00)
MD Retarder, Clear Active Indicator
166°C (330°F)
159°C (318°F)
168°C (335°F)
162°C (323°F )
168°C (335°F)
162°C (323°F)
HD Retarder, Light On
HD Retarder, Light Off
138°C (281°F)
131°C (268°F)
141°C (285°F)
135°C (275°F)
+
166°C (330°F)
159°C (318°F)
HD Retarder, Set Hot Code (61 00)
HD Retarder, Clear Active Indicator
138°C (281°F)
131°C (268°F)
168°C (335°F)
162°C (323°F)
168°C (335°F)
162°C (323°F)
MD Retarder, Capacity Reduction
(Total Reduction Over Temperature Range)
166–182°C
(330–360°F)
149–182°C
(300–360°F)
149–182°C
(300–360°F)
HD Retarder, Capacity Reduction
(Total Reduction Over Temperature Range)
138–182°C
(280–360°F)**
149–182°C
(300–360°F)
149–182°C
(300–360°F)
MD Retarder, Preselect On
Preselect remains on until the retarder is deactivated.
NONE 143°C (289°F) (1st) 143°C (289°F)
HD Retarder, Preselect On (V7)
HD Retarder, Preselect On (V6)
Preselect remains on until the retarder is deactivated.
-------
103°C (218°F) (1st)
143°C (289°F) (1st)
-------
143°C (289°F)
* No retarder calibrations were made prior to the release of Version 6E (501) software in 8/92.
** The Version 6E (501) capacity reduction set point temperature for HD retarders is output speed-dependent; however, the total reduction is always
13.5% between the set point temperature and 360°F.
+ Effective 3/13/95, these values become 330°F Light On and 318°F Light Off.
CODE 61 XX — RETARDER FLUID HOT
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