Starting System: Other GMC Yukon Denali

SYSTEM TESTS

Note. The following tests assume that engine and battery are operating normally and are at operating temperature, battery is charged, battery connections are okay, there are no engine problems that would cause a no-start condition, and no diagnostic trouble codes are present.

SLOW OR NO CRANK ONLY AFTER EXTENDED PERIODS OF VEHICLE NON-USE

There may be a parasitic load on electrical system. See PARASITIC LOAD EXPLANATION & TEST PROCEDURES article in GENERAL INFORMATION.

ENGINE DOES NOT CRANK, STARTER SOLENOID DOES NOT CLICK

1. Set parking brake. Move shift lever to Park or Neutral position (A/T) or depress clutch pedal (M/T). Connect DVOM between ground and starter solenoid "S" terminal (Purple wire). Turn ignition switch to START position. If battery voltage exists, go to step 13. If battery voltage does not exist, go to next step.
2. Locate and disconnect starter relay. See «COMPONENT LOCATIONS»(ref-8515-S06434312362000090800000). Connect test light between ground and starter relay switch feed circuit cavity No. 30 (Red wire). (Scheme 7) See «WIRING DIAGRAMS»(ref-8515-S39222874062000090800000). If test light illuminates, go to next step. If test light does not illuminate, go to step 14.
3. Connect 30-amp fused jumper between starter relay switch feed circuit cavity No. 30 (Red wire) and starter relay switch output circuit cavity No. 87 (Purple wire). If starter solenoid clicks, go to next step. If starter solenoid does not click, go to step 15.
4. Disconnect Purple wire from starter solenoid "S" terminal. Connect test light between battery voltage and starter relay coil feed circuit cavity No. 85 (Purple/White wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 16.
5. Connect DVOM between starter relay coil feed circuit cavity No. 85 (Purple/White wire) and starter relay coil ground circuit cavity No. 86 (Black wire). Move shift lever to Park or Neutral position (A/T) or depress clutch pedal (M/T). Turn ignition switch to START position. If battery voltage exists, go to step 17. If battery voltage does not exist, go to next step.
6. If vehicle is equipped with manual transmission, go to next step. If vehicle is equipped with automatic transmission, go to step 9.
7. Locate and disconnect Black 4-pin Clutch Pedal Position (CPP) switch. Connect DVOM between ground and CPP switch connector terminal "A" (Purple wire). (Scheme 8) Turn ignition switch to START position. If battery voltage exists, go to next step. If battery voltage does not exist, go to step 11.
8. Connect 30-amp fused jumper between Black 4-pin CPP switch connector terminals "A" (Purple wire) and "C" (Purple/White wire). Depress clutch pedal and move shift lever to Neutral. Turn ignition switch to START position. If engine cranks, go to step 18. If engine does not crank, go to step 19.
9. Locate and disconnect Gray 7-pin Park/Neutral Position (PNP) switch. Connect DVOM between ground and Gray 7-pin PNP switch connector terminal "E" (Purple wire). (Scheme 9) Turn ignition switch to START position. If battery voltage exists, go to next step. If battery voltage does not exist, go to step 11.
10. Connect 30-amp fused jumper between Gray 7-pin PNP switch connector terminals "E" (Purple wire) and "G" (Purple/White wire). Turn ignition switch to START position. If engine cranks, go to step 20. If engine does not crank, go to step 21.
11. Locate Black 48-pin in-line harness connector C266, under left side of instrument panel, left of steering column near bulkhead. Connect DVOM (backprobe) between ground and Black 48-pin in-line harness connector C266 terminal D1 (Yellow wire). (Scheme 10) Turn ignition switch to START position. If battery voltage exists, go to step 22. If battery voltage does not exist, go to next step.
12. Connect DVOM (backprobe) between ground and Black 48-pin in-line harness connector C266 terminal D5 (Red wire). If battery voltage exists, go to step 23. If battery voltage does not exist, go to step 24.
13. Clean starter and engine block mounting surfaces. Retest operation. If engine will still not crank, replace starter. See «STARTER»(ref-8515-S03776685742000090800000) under REMOVAL & INSTALLATION. Retest operation.
14. Install starter relay. Repair open in Red wire between starter relay switch feed circuit cavity No. 30 and IGN-A (40-amp) fuse located in underhood fuse/relay center. Retest operation.
15. Install starter relay. Repair open or high resistance in Purple wire (supply voltage circuit to starter solenoid) between starter relay switch output circuit cavity No. 87 and starter solenoid "S" terminal. Retest operation.
16. Install starter relay. Repair open or high resistance in Black wire between starter relay switch ground circuit cavity No. 86 and ground connection G105, located on right front side of engine block (gas) or at right rear intake manifold bolt (diesel). Retest operation.
17. Replace starter relay. Retest operation.
18. Check for poor connection to CPP switch. Repair as necessary and retest operation. If connections to CPP switch check okay, replace CPP switch. See «CLUTCH PEDAL POSITION (CPP) SWITCH»(ref-8515-S29133632692000090800000) under REMOVAL & INSTALLATION. Retest operation.
19. Repair open in Purple/White wire between CPP switch connector terminal "C" and starter relay coil feed circuit cavity No. 85. Retest operation.
20. Check operation and adjustment of PNP switch. See appropriate AUTOMATIC TRANSMISSION SERVICING article in AUTOMATIC TRANSMISSIONS. Check for poor connection to PNP switch. Repair as necessary and retest operation. If PNP switch connection and adjustment are okay, replace PNP switch and retest operation.
21. Repair open in Purple/White wire between PNP switch connector terminal "G" and starter relay coil feed circuit cavity No. 85. Retest operation.
22. Remove CRANK (10-amp) fuse located in instrument panel fuse block. Using test light connected to ground, probe both CRANK fuse terminals inside instrument panel fuse block while turning ignition switch to START position. If test light does not illuminate on either terminal, repair open in Yellow wire between Black 48-pin in-line harness connector terminal D1 and appropriate CRANK fuse terminal. If test light illuminates on one terminal, repair open in Purple wire between appropriate CRANK fuse terminal and PNP switch (A/T) or CPP switch (M/T). Retest operation.
23. Replace ignition switch. See appropriate STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT. Retest operation.
24. Repair open in Red wire between Black 48-pin in-line harness connector terminal D5 and IGN-A (40-amp) fuse located in underhood fuse/relay center. Retest operation.

Scheme 7

Scheme 8

Scheme 9

Scheme 10

ENGINE DOES NOT CRANK, SOLENOID CLICKS

1. Check for high resistance in Red wire between positive battery terminal and underhood fuse/relay center. See «WIRING DIAGRAMS»(ref-8515-S39222874062000090800000) . Repair as necessary and retest operation. If Red wire checks okay, go to next step.
2. Check for high resistance in ground circuit between battery and starter. Repair as necessary and retest operation. If ground circuit checks okay, go to next step.
3. Check for high resistance in Purple wire between underhood fuse/relay center and starter solenoid "S" terminal. Repair as necessary and retest operation. If Purple wire checks okay, go to next step.
4. Check for poor connections to underhood fuse/relay center. Repair as necessary and retest operation. If connections to underhood fuse/relay center check okay, go to next step.
5. Check for poor connections at starter solenoid. Repair as necessary and retest operation. If connections to starter solenoid check okay, go to next step.
6. Replace starter. See «STARTER»(ref-8515-S03776685742000090800000) under REMOVAL & INSTALLATION. Retest operation.

PG260 (GASOLINE)

Information is not available from manufacturer.

28MT (DIESEL)

Note. Do not attempt to disassemble solenoid assembly, clutch drive assembly, brush holder assembly, armature assembly, or frame and field assembly. These items are serviced as complete assemblies only.

Preliminary Tests

Remove starter from vehicle. See STARTER under REMOVAL & INSTALLATION. Check starter components for damage such as cracks, distortion or structural damage. Check for stripped or crossed threads. Check solenoid for cut or torn boot. Replace any components or assemblies as necessary.

Armature

1. Inspect armature for gear teeth that are broken or show evidence of step wear or root interference. DO NOT turn commutator in lathe. If commutator is rough or damaged, polish surface with 400 grit polishing cloth. Thoroughly clean metal dust from between commutator bars. If commutator surface cannot be repaired in this manner, replace armature.
2. Replace armature if outside diameter is less than 1.4" (36 mm) or if undercut depth at any point is less than .008" (.20 mm). DO NOT undercut insulation.
3. Using growler, check armature for shorts. Hold a flat steel strip on armature parallel to armature core or shaft. Rotate armature in growler. Steel strip will vibrate on area of short circuit.
4. Using self-powered test light, place one lead on armature shaft and other lead on commutator. Test light should not illuminate. If test light illuminates, armature is shorted or grounded and must be replaced.
5. Inspect points where armature conductors join commutator and/or individual commutator segments for signs of burning or arcing. This indicates open circuits.

Brush Holder

Check for loose riveted joints and cracked or broken insulation. Check brushes for excessive wear. Minimum allowable brush length is .47" (12 mm). Replace brush holder if damaged or if worn below specification. Verify brush spring tension is 10-11 lbs. (4.5-5.0 kg). Replace brush springs if tension is not within specification or springs are distorted or discolored.

Drive End Housing & Bushing

Inspect drive end housing bushing for scoring or other damage. Replace bushing if damaged. Hold armature or driveshaft while slowly rotating outer bearing race by hand. Bearing should turn freely without binding. Replace any damaged bearings.

Solenoid Windings

Using DVOM, measure resistance of solenoid pull-in and hold-in windings in a series by measuring between motor terminal and solenoid case. A reading of more than 1.3 ohms indicates a break or fault in winding continuity. A reading of less than .8 ohm, indicates a short or ground in winding circuit. Replace starter solenoid if resistance is extremely high or very low.