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.
1988 Chevrolet Spectrum ExpressFACTORY OEM SERVICE PROCEDURE
Code 24 (VSS)
- Verify speedometer operation. Disconnect speedometer cable at transaxle. Turn ignition on and check voltage at ECM harness connector A10 and ground while turning speedometer cable slowly.
- If voltage varies from 1-6 volts, problem is intermittent. If voltage is 8-12 volts and steady, check VSS harness for open or short. If harness is good, replace VSS.
- If voltage is below one volt, disconnect harness at VSS and check voltage. With ignition on, if voltage is above 10 volts, replace VSS.
- If voltage is below 10 volts, check VSS harness to ECM connector A10 for shorting to ground. If harness tests good, repair harness connector or replace ECM.
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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