03DelcoRemy Diagnostic Manual130004222020

Page 18 4. If vehicle now starts properly, make sure starter mounting bolts are tight and proceed to Alternator Wiring Test. 3-23. AVAILABLE CRANKING VOLTAGE . If batteries, switches and wiring have been checked and starter still cranks slowly, check for available voltage at the starter while cranking. Proceed as follows: Test 1. Have assistant press push-button with key switch on while measuring voltage across solenoid BAT terminal and starter ground terminal. 2. If voltage is 9.0 volts (18 volts for 24-volt system) or less while cranking, check battery interconnecting cables as specified in next step. 3. Measure voltage across each battery while cranking. Touch voltmeter leads to terminals of every battery. If difference between any two battery readings in same box is more than 0.5 volt, or if any cable or connection feels warm to the touch, check or replace interconnecting cable(s) as required. 3-24. RING GEAR AND PINION CHECK. One final check before replacing the starter is to inspect the pinion and ring gear. Inspect 1. Pinion and ring gear visually while assistant bars engine over. Be sure to check entire ring gear. 2. If pinion is damaged, replace starter. If ring gear is damaged, replace ring gear and note that there is a likelihood the pinion also may be damaged. 3-25. STARTER REPLACEMENT. After making all tests specified, if the vehicle does not crank properly, the problem is with the starter or engine. Replace the starter and re-check to see if engine cranks properly. If not, then look for a mechanical problem with the engine. 3-26. ALTERNATOR WIRING TEST This procedure is the first step in checking out the charging system: output of the alternator, batteries and accessory loads with a minimum of voltage loss. Any loss slows the rate of charge to the batteries and could cause the batteries to be partially discharged. Discharged batteries can result in starter damage. Low output voltage can cause improper performance of other vehicle electrical components. 3-27. TEST PROCEDURE (See Figure 3-8). Instead of using the alternator output, this test uses the same current but draws it from the batteries. Using a carbon pile load, current flows in reverse through the circuit with the engine off. Proceed as follows: NOTE 24-volt systems must be connected to a temporary 12-volt configuration as described for Battery Cable Test, paragraph 3-8. NOTE Before proceeding with this test, make sure that the batteries have been tested and that the terminal has been cleaned and tightened. CAUTION Alternator output terminal is at battery voltage. Engine must be off for this test. Connect 1. Carbon pile to alternator output terminal and to ground. NOTE Jumper wires may be used to extend voltmeter leads if necessary. 2. Digital voltmeter set on low scale from alternator output terminal to positive battery terminal. Test 1. Turn on and adjust carbon pile to alternator-rated amperage output. 2. Read voltmeter and record voltage (V24), which is positive circuit voltage loss. Immediately turn off carbon pile. Connect 1. Digital voltmeter set on low scale from alternator ground to negative battery terminal. Test 1. Turn on and adjust carbon pile to alternator rated amperage output. 2. Read voltmeter and record voltage (V25), which is negative circuit voltage loss. Immediately turn off carbon pile. 3. Add positive circuit loss (V24) and negative circuit loss (V25) to get total system loss (V23). This loss (V23) shall not exceed: • 12-volt system - 0.500 volt maximum voltage loss • 24-volt system - 1.000 volt maximum voltage loss 4. Replace cables or repair circuits with excessive voltage loss.