Pelican Parts: Bosch ECU Tester Operating Instructions

Checking equipment

The most significant piece of equipment for checking the injection system is the Bosch tester. It is used to test all the information transmitters as well as the pump and injection valves according to an accurately determined test program Within this test program the fuel ring line is also tested for pressure and the presence of leaks. It is important that all these points are checked during a test.

Before starting the test, complete the following: Switch off the ignition to deenergize the control unit. Remove the control unit. Pull the multiple plug out of the control unit and connect the plug of the tester to the multiple plug of the cable line. Switch on the ignition and check all functions in accordance with the test program.

Installation

Install in reverse procedure of removal; note the following: Prior to installing the intake connections again, adjust the throttle valve switch.

The fuel injection system can be checked accurately only with the tester. When testing acc. to the Check List, deviations from the rated value will be noticed. Whatever has to be done in such cases in addition, is shown in the following list

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Check. step	Result	Possible Cause (remedy)
1 Voltage I	No indication	Interruption: terminal 85 on relay I no voltage (check whether terminal 15/ignition coil has voltage, check line), terminal 30 on relay I no voltage (check acc. to Wiring Diagram), terminal 86 on relay I no earth connection (check earth connection), connection between terminal 87 of relay I and terminal 16 control unit interrupted (check line 16).
	Voltage below 11 Volt	Transfer resistance in line 16/control unit or on relay contacts (check line, change relay I)
2 Voltage II 3 Voltage Starter	Similar to checking step 1, but check line to terminal 24 control unit
	No voltage, starter is running	Line interruption from starter solenoid switch to control unit (check line 18).
	No voltage, starter is not running	Ignition starter lock defective , line interruption
	Voltage below 9 Volt	Battery discharged. voltage drop too high in line from ignition starter lock to terminal 50 of starter solenoid switch (check line with volt meter).
4 Align to infinity	If no full deflection is obtained on instrument, battery voltage in vehicle is too low. Also refer to checking steps 1 and 2.
Pressure feeler earth connection	Resistor 0	Earth connection in supply line or on pressure feeler (pull plug on pressure feeler , if indication is then infinity, exchange pressure feeler. If indication remains unchanged at 0, short circuit in line 7.8. 10, 15. exchange cable line).
	Indication under infinity but not 0	Insulation damage (similar to 5, resistor 0).
5 Pressure feeler primary	Rated value approx. 90 ohm resistance considerably less	Insulating damage (pull plug on pressure feeler , if indication is then infinity, exchange pressure feeler).
	Resistor 0	Earth connection , short circuit of primary line (pull plug on pressure feeler , if indication is then infinity, exchange pressure feeler).
	Rated value approx. 90 ohm resistance considerably higher	High transition resistance (check plug and lines for corrosion or interruption).
	Resistor infinite resistance	Interruption (Bridge on plug as shown in illustration. If indication is 0, exchange pressure feeler. If indication is infinity, repair line).

Check. step	Result	Possible cause (remedy)
6 Pressure feeler secondary	Similar to 5 rated value but approx. 350 ohm	Similar to 5 at resistance infinity, bridge the two other terminals.
7 Ignition distributor contact I	Resistance higher than 0 or lower than infinite resistance	If the needle of the instrument does not deflect during "Starting" or remain in one position -infinity or 0 - renew contacts. (Replace contact insert.)
8 Ignition distributor contact II
9 Throttle valve switch I then throttle valve switch II	Needle remains at infinity or needle remains not at infinity when throttle valve is returned	Throttle valve switch defective (replace)
	Needle remains at 0	Short circuit (pull plug on throttle valve switch · if needle is then infinity, replace throttle valve switch, otherwise cable line)
10 Throttle valve switch III	Resistance infinity with throttle valve lever in position "Idling"	Throttle valve switch wrongly set or interruption in supply line. (Check adjustment, pull plug, bridge. If then still infinity, replace cable line, otherwise replace throttle valve switch).
	Resistance 0 ohm with throttle valve opened more than 2°	Throttle valve switch wrongly adjusted or short circuit in supply line. Pull plug, if indication is then still 0, adjust or replace cable line · otherwise throttle valve switch).
11 Temperature feeler I (in intake distributor)	Rated value 350 ohm resistance higher or lower	Rated value applies at 20°C (68°F). Resistance decreases with increasing temp. Feeler is in order · if no 0 or infinity is measured.
	Indication infinite ohm	Interruption. (Bridge. if indication is then 0, replace temperature feeler, otherwise cable line).
	Indication 0 ohm	Short circuit. (Pull plug, if indication remains unchanged. cable defective. If indication is infinity , replace temperature feeler).
12 Temperature feeler II cylinder head	Similar to 11 with the following deviations: rated value 2.5 k ohm, instead of bridging: hold plug of cable line to mass.
13 Valves (Resist.)	Resistor 0 ohm	Short circuit in supply line or on valve. (Pull plug on respective valve · if indication is then infinity. replace valve. otherwise replace cable line).
	Resistor infinite ohm	Interruption in supply line or in valve coil. (Bridge contacts in valve plug, if indication is then infinity , cable line defective. If then 0, valve defective).
	Rated value 2.4 ohm at 20°C · resistance higher, but not infinity	Earth connection of valves is badly connected to crankcase or flat plug connection is badly plugged (use contact spray, tighten earth connection screw).
	Resistor under 2.4 ohm but not 0	Interturn short circuits of valve (replace)

Check. step	Result	Possible cause (remedy)
14 Pressure in ring line	Pressure above 2 kp/cm²(28.4 psi) Pressure below 2 kp/cm²	^{Pressure regulator wrongly adjusted (adjust); if not adjustable , pressure regulator defective (replace).}
14 Pressure in ring line	No pressure established (pump does not start)	Pump without power. (Pull two-pole plug on pump housing and measure voltage with voltmeter. Voltage should be indicated , when button "Pump" on tester is pushed.) Indication 12 Volt: Replace pump. Indication 0 Volt: Listen whether pump relay (under instrument panel) attracts. If yes: Line interruption from pump relay, terminal 87, to 2-pole plug or from 2-pole plug to mass connection, or pump relay defective. If no: Line interruption from terminal 87 voltage supply relay to pump relay, terminal 86 or 85, to line 19 in cable tree (line connector in engine compartment). If line in order, replace pump relay.
15 Pressure drops immediately upon releasing button "Pump" slowly, but steadily	Leak in pressure system (from fuel pump to pressure regulator). Disconnect fuel ring line prior to injection valve with self-made clamp or suitable pliers. If there is no pressure loss, the leak is in the pressure line or pump; if there is a loss of pressure the leak is in the ring line connection to the injection valves, in the injection valves themselves or on the pressure regulator. Establish pressure several times during the test, if required. Sight test for leaking hose connections (also pressure gauges). If not: remove the two valve groups one after the other, also remove cold starting valve. Push button "Pump" and check for leaks by sight test. Valve opening may become wet. (But there should be nor more than 2 drops per minute). If no leak is found, replace pressure regulator.