Test Point 16 - Upshift Indicator (Only USA)
TEST POINT 16 - DME 944Upshift Indicator (Only USA)
Function
An illuminated arrow is located in the upper half of the tachometer. It lights up "yellow", if the instantaneous engine power is not conforming with favorable fuel consumption. This is an indication for the driver to shift up into the next higher gear, since the same performance is possible in the next higher gear with lower fuel consumption.
The upshift indicator works in gears 1-4 and remains illuminated until the instantaneous operating range is changed or the next higher gear is engaged. It does not come on or goes out when coasting, full throttle accelerating or incorrect operating (e. g. clutch pedal pressed and engine running at high speed).
The brightness of the illuminated arrow is taken back automatically when switching on the car lights, to avoid disturbing glare.
The entire operating electronics is integrated in the tachometer and cannot be replaced separately. The upshift indicator cannot be installed in older models.
Activation of the upshift electronics is accomplished chiefly with the circuit of the instrument cluster, so that separate (leading to the outside) wire connections have been omitted.
Activating Signals: a) Temperature signal (coolant temperature sensor)
b) Road speed signal (speedometer)
c) Engine speed signal (tachometer)
d) Injection time (ti) signal (on instrument cluster term. 5 (middle)
e) Also an internally programed triggering circuit, depending on the instantaneous engine speed and injection time change.
Checking
Proceed as described below to pinpoint a fault in case of upshift indicator failure.
The car should be driven on a level road/street or on a dynamometer before checking separate signals. Then accelerate the engine slowly to the following test speeds.
Move off in 1st gear, accelerate engine to 2100 ± 30 rpm*, then shift
to 2nd gear, accelerate engine to 2300 ± 30 rpm*, then shift
to 3rd gear, decelerate engine to 2200 ± 30 rpm*, then shift
to 4th gear, accelerate engine to 2400 ± 30 rpm* and finally shift
to 5th gear.
* Upshift indicator should light up when reaching the test speed.
Test speeds will be higher by 400 ± 30 rpm in 1st and 2nd gears or 300 ± 30 rpm in 3rd gear when the engine is still cold, i.e. coolant temperature below 40 °C (sensor resistance >= 288 ohm - temperature gage needle in area of first white section).
Important!
The indicator does not come on or goes out when operating clutch, coasting or accelerating with throttle wide open (idle - full load).
Check the following points, if the upshift indicator does not light up in the different gear speeds.
1. Function of tachometer, speedometer and coolant temperature gage okay.
2. Injection time (ti) signal of DME control unit. Connect workshop oscilloscope on multiple-pin plug term. 1 via the DME control unit (plug remains connected).
Start engine - injection time (ti) signal must appear on screen in form of rectangular pulses.
Number of pulses (frequency) will increase while accelerating.
Check DME control unit plug connection, if signal is not visible. Or exchange control unit for comparison and repeat test.
3. If test results are positive up to this point, the instrument cluster has to be removed. First leave instrument plugs connected.
a) Term. 3 (left) must have coolant temperature signal (ohmmeter).
b) Term. 15 (middle) must have rectangular signal when rear wheels are turned - speedometer signal (oscilloscope).
c) Term. 5 (middle) must have ti signal (oscilloscope).
d) Term. 16 (middle) must have + 30 (test lamp).
If no fault can be detected - check printed circuit; if applicable replace tachometer with integrated display electronics.