SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSOLDSMOBILE1998ACHIEVA 3.1 M, 4T40E/MN4REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 13 (BODY CONTROL MODULE)DIAGNOSTIC TESTSDTC B1488: GENERATOR "L" TERMINAL HIGHTESTING
1998 Oldsmobile Achieva 3.1 M, 4T40E/MN4

DTC B1488: Generator "L" Terminal High: Testing

1998 Oldsmobile Achieva 3.1 M, 4T40E/MN4SECTION Testing
WARNING: This page is about a different car, the 1998 Oldsmobile Cutlass and 1998 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
  1. If BFC diagnostic system check was performed, go to next step. If BFC diagnostic system check was not performed, see procedures in BFC DIAGNOSTIC SYSTEM CHECK  .
  2. Turn ignition switch to RUN position, with engine off. Using DVOM, check voltage by backprobing between generator harness connector terminal "B" (Red wire) and ground. If about zero volts exists, go to step 5). If about zero volts does not exist, go to next step.
  3. Disconnect generator connector. On 2.4L, disconnect PCM Blue 80-pin connector C1. On 3.1L, disconnect PCM Clear 80-pin connector C2. On 2.4L, use DVOM to check resistance between PCM harness connector C1, terminal No. 74 (Red wire) and generator harness connector terminal "B" (Red wire). On 3.1L, use DVOM to check resistance between PCM harness connector C2, terminal No. 35 (Red wire) and generator connector terminal "B" (Red wire). If resistance is 0-2 ohms, go to next step. If resistance is not 0-2 ohms, go to step 7).
  4. Reconnect all connectors and components. Turn ignition switch to RUN position, with engine off. On 2.4L, use DVOM to check voltage by backprobing between PCM harness connector C1, terminal No. 74 (Red wire) and ground. On 3.1L, use DVOM to check voltage by backprobing between PCM harness connector C2, terminal No. 35 (Red wire) and ground. If battery voltage exists, go to step 6). If battery voltage does not exist, go to step 8).
  5. Using scan tool, read PCM "L" terminal status. If "L" terminal input is low, go to step 9). If "L" terminal is not low, go to step 8).
  6. Replace generator. See GENERATOR & REGULATOR article in ELECTRICAL. Go to step 9).
  7. Repair open in Red wire between generator and PCM connector C1 (2.4L) or connector C2 (3.1L). Go to step 9).
  8. Replace PCM. See REMOVE/INSTALL/OVERHAUL article in ENGINE PERFORMANCE section. Go to next step.
  9. Clear DTCs. Perform BFC DIAGNOSTIC SYSTEM CHECK  .


  1. If BFC diagnostic system check was performed, go to next step. If BFC diagnostic system check was not performed, see procedures in BFC DIAGNOSTIC SYSTEM CHECK  .
  2. Turn ignition switch to RUN position, with engine off. Using DVOM, check voltage by backprobing between generator harness connector terminal "B" (Red wire) and ground. If about zero volts exists, go to step 5). If about zero volts does not exist, go to next step.
  3. Disconnect generator connector. On 2.4L, disconnect PCM Blue 80-pin connector C1. On 3.1L, disconnect PCM Clear 80-pin connector C2. On 2.4L, use DVOM to check resistance between PCM harness connector C1, terminal No. 74 (Red wire) and generator harness connector terminal "B" (Red wire). On 3.1L, use DVOM to check resistance between PCM harness connector C2, terminal No. 35 (Red wire) and generator connector terminal "B" (Red wire). If resistance is 0-2 ohms, go to next step. If resistance is not 0-2 ohms, go to step 7).
  4. Reconnect all connectors and components. Turn ignition switch to RUN position, with engine off. On 2.4L, use DVOM to check voltage by backprobing between PCM harness connector C1, terminal No. 74 (Red wire) and ground. On 3.1L, use DVOM to check voltage by backprobing between PCM harness connector C2, terminal No. 35 (Red wire) and ground. If battery voltage exists, go to step 6). If battery voltage does not exist, go to step 8).
  5. Using scan tool, read PCM "L" terminal status. If "L" terminal input is low, go to step 9). If "L" terminal is not low, go to step 8).
  6. Replace generator. See GENERATOR & REGULATOR article in ELECTRICAL. Go to step 9).
  7. Repair open in Red wire between generator and PCM connector C1 (2.4L) or connector C2 (3.1L). Go to step 9).
  8. Replace PCM. See REMOVE/INSTALL/OVERHAUL article in ENGINE PERFORMANCE section. Go to next step.
  9. Clear DTCs. Perform BFC DIAGNOSTIC SYSTEM CHECK  .
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

Shop Manual-Ready ToolsFree Quote CheckQuote Shield Pro

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.