1985-1998 [Subscribe to Daily Digest] |
Low EDU Fuel Consumption Reading
CATEGORY
Electrical
SECTION
3
PAGE
44
ISSUE
06/93-0349
CODE
381
Subject:
Excessively Low EDU Average Fuel
Consumption Reading
Application:
1990- 9000 Models
A service procedure has been developed to remedy complaints of low fuel consumption
readings. For example, a customer may complain that the average fuel consumption
readout on the EDU is 29 MPG, while their actual (calculated) consumption is 24 MPG.
When the ignition is switched off, voltage remains present on the speed input (pin 9)
of the EDU for an additional five minutes.
On some cars with numerous systems connected to the speedometer's speed output, this
voltage may be above the EDU's threshold level and cause it to continue counting the
distance covered (mileage) during the five minutes it is active after the car is shut
off.
This affects the EDU's calculation of average fuel consumption, causing it to show a
varying, excessively low figure while "distance to empty" is correspondingly too
high.
The fault is also noticeable in that the average fuel consumption figure will change
when the car has been parked overnight. The fault can be remedied by installing a
diode between the speed signal and switched power.
Cars Affected:
1990- Saab 9000 Models up to:
P1011827 inclusive, manual gearbox
P1011697 inclusive, automatic transmission
Parts:
Service kit 44 39 295, which contains the following items:
^ Diode 1N 4140 with soldered leads, one yellow and one green.
^ Cable terminals 91 20 783
^ 1 Cable tie 79 71 864
Action:
1. Remove the clock or DCC/SCC from the instrument panel, Figure 1.
2. If the car is equipped with a clock:
Unplug the 3-pin connector and the 8-pin HB-A connector (122) from the rear of
the clock.
Locate the 8-pin H8-B connector (122) in the wiring behind the clock. (Location
of this connector may vary.)
The connector can be identified by the colors of the leads.
Pin Color of Lead Pin Color of Lead
1 126 RD (red) 6 617 BK (black)
2 773 8K (black) 7 796 GY (grey)
8 779 GN (green)
If the car is equipped with a DCC/SCC:
Unplug the two connectors, H8-A and HB-B (122) at the rear of the DCC/SCC.
3. Remove pin 6 and lead 777YE (yellow) from connector H8-A. Cut off the terminal
and strip the insulation from the lead. Crimp this lead and the yellow diode
lead to one of the cable terminals 91 20 783.
Plug the terminal back into the connector receptacle for pin 6, Figure 2.
4. Remove pin 8 and lead 779GN (green) from connector H8-B. Cut off the terminal
and strip the insulation from the lead. Crimp this lead and the green diode lead
to the other cable terminal 91 20 783. Fit the terminal back into the connector
receptacle for pin 8, Figure 3.
5. Secure the diode in place using a cable tie, Figure 4.
6. If the car is equipped with a clock:
Plug the connectors back onto the clock. Fasten the unused B-pin connector to
the wiring by means of a cable tie (not included in the kit) to avoid unwanted
noise, Figure 5.
If the car is equipped with DCC/SCC:
Plug the connectors back onto the DCC/SCC, Figure 5.
Warranty Information:
For warranty repairs, use failure coding 38138-67-0-01-05. Time allowance is labor
operation no. 38131 (0.2 hours).
posted by 142.161....
, Sun, 1 Nov 2009 22:04:18
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