Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1999 Chevrolet Cutaway 7.4 JFACTORY OEM SERVICE PROCEDURE
Scan Tool Inoperative/Does Not Communicate With Components
- If scan tool powers up, go to next step. If scan tool does not power up, go to step 5 .
- Ensure scan tool is operating correctly by connecting scan tool to a different vehicle. If scan tool is functioning properly, return to original vehicle and go to next step. If scan tool is malfunctioning, refer to scan tool owners manual.
- Turn ignition to OFF position. Disconnect scan tool from Data Link Connector (DLC). Inspect for poor connections/terminal tension at DLC terminals No. 2, 4, 5 and 16. See Figure
. If there is no fault with DLC, go to next step. If there is any fault, repair as necessary and perform diagnostic system check for module that is not communicating. See the following.
- See SIR DIAGNOSTIC SYSTEM CHECK in AIR BAG RESTRAINT SYSTEM article in RESTRAINTS.
- See DIAGNOSTIC SYSTEM OPERATION CHECK - ANTI-THEFT in ANTI-THEFT SYSTEMS article.
- See DIAGNOSTIC SYSTEM CHECK in ANTI-LOCK BRAKES article in BRAKES.
- See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in SELF-DIAGNOSTICS - DIESEL article in ENGINE PERFORMANCE.
- See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in SELF-DIAGNOSTICS - GASOLINE article in ENGINE PERFORMANCE.
- Test DLC ground circuits at terminals No. 4 and 5 for an open. See Figure
and Figure
. If there is no fault with ground circuits, go to next step. If there is fault with ground circuits, repair as necessary and perform diagnostic system check for module that is not communicating. See the following.
- See SIR DIAGNOSTIC SYSTEM CHECK in AIR BAG RESTRAINT SYSTEM article in RESTRAINTS.
- See DIAGNOSTIC SYSTEM OPERATION CHECK - ANTI-THEFT in ANTI-THEFT SYSTEMS article.
- See DIAGNOSTIC SYSTEM CHECK in ANTI-LOCK BRAKES article in BRAKES.
- See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in SELF-DIAGNOSTICS - DIESEL article in ENGINE PERFORMANCE.
- See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in SELF-DIAGNOSTICS - GASOLINE article in ENGINE PERFORMANCE.
- Ensure battery power is present at DLC terminal No. 16. See Figure . If there is battery power, go to next step. If there is not battery power, go to step 8 .
- Test Class 2 serial data circuit for an open or short to ground in 1807 circuit wire. See Figure
. If there is no fault with the 1807 circuit, go to next step. If there is fault with the 1807 circuit, repair as necessary and perform diagnostic system check for module that is not communicating. See the following.
- See SIR DIAGNOSTIC SYSTEM CHECK in AIR BAG RESTRAINT SYSTEM article in RESTRAINTS.
- See DIAGNOSTIC SYSTEM OPERATION CHECK - ANTI-THEFT in ANTI-THEFT SYSTEMS article.
- See DIAGNOSTIC SYSTEM CHECK in ANTI-LOCK BRAKES article in BRAKES.
- See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in SELF-DIAGNOSTICS - DIESEL article in ENGINE PERFORMANCE.
- See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in SELF-DIAGNOSTICS - GASOLINE article in ENGINE PERFORMANCE.
- Disconnect each module one at a time while monitoring Class 2 circuit for a short. If a short is removed after a module is disconnected, replace module that is shorting circuit. Perform diagnostic system check for module that was shorting circuit. See the following.
- See SIR DIAGNOSTIC SYSTEM CHECK in AIR BAG RESTRAINT SYSTEM article in RESTRAINTS.
- See DIAGNOSTIC SYSTEM OPERATION CHECK - ANTI-THEFT in ANTI-THEFT SYSTEMS article.
- See DIAGNOSTIC SYSTEM CHECK in ANTI-LOCK BRAKES article in BRAKES.
- See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in SELF-DIAGNOSTICS - DIESEL article in ENGINE PERFORMANCE.
- See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in SELF-DIAGNOSTICS - GASOLINE article in ENGINE PERFORMANCE.
- Repair open or high resistance in 840 circuit wire. See Figure
. Perform diagnostic system check for module that is not communicating. See the following.
- See SIR DIAGNOSTIC SYSTEM CHECK in AIR BAG RESTRAINT SYSTEM article in RESTRAINTS.
- See DIAGNOSTIC SYSTEM OPERATION CHECK - ANTI-THEFT in ANTI-THEFT SYSTEMS article.
- See DIAGNOSTIC SYSTEM CHECK in ANTI-LOCK BRAKES article in BRAKES.
- See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in SELF-DIAGNOSTICS - DIESEL article in ENGINE PERFORMANCE.
- See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in SELF-DIAGNOSTICS - GASOLINE article in ENGINE PERFORMANCE.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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