Why won't my Cadillac Eldorado start, or why does the battery keep dying?

Short answer: If the lights come on but your Eldorado won't start, first figure out whether it cranks. A weak battery can light the dash but not turn the starter, and corroded positive battery cables are common on these GM cars. If the battery keeps draining and the alarm goes off randomly, members suspected the retained accessory power relay staying on, or the trunk pull-down motor and lamp; a shop with an amp clamp can trace the circuit.

Symptom: Dash lights and accessories work, but the car won't start. Or the security system goes off randomly, the clock flickers, and even a new battery goes dead.

What to check first

1. Tell whether it cranks (engine turns over) or just clicks or does nothing.
2. Try a jump start, and try starting in neutral in case the park switch is the problem.
3. Check the positive battery cable and its ends for corrosion under the insulation.
4. For a drain, check whether accessories stay on after the key is off. That points at the retained accessory power relay.
5. Unplug the trunk pull-down motor and trunk lamp to see if the drain stops, then have the draw traced with an amp clamp.

Likely causes

1. Weak battery or corroded battery cables. Enough for lights but not the starter.
2. Starter or neutral safety switch. Ruled in or out by the neutral test and crank check.
3. Retained accessory power relay stuck on. A member's suspect for a drain with random alarms.
4. Trunk pull-down motor or lamp. The dealer's suspect in the 1997 thread.

What it usually costs

In one thread a member said the dealer wanted about $700 for a guess at the trunk motor. Members said a shop with an amp clamp and wiring diagram can usually narrow a drain down in about an hour.

Is it safe to keep driving?

A car that won't start is a nuisance, but a parasitic drain can strand you. If the alarm and clock act up, have it traced soon. Verify with a mechanic.

DIY or shop?

DIY for battery and cable checks and unplugging the trunk motor. Tracing a drain with a wiring diagram is usually a shop job.

Recalls, bulletins and complaints in plain words

• Related recalls: NHTSA lists these recalls touching this area of the Cadillac Eldorado: 95V224000 (1996-1996 model years, equipment). Check your VIN at nhtsa.gov/recalls. If your car is part of this recall, the dealer fixes it for free.
• In plain words: on some 1996 Eldorados, a short in the instrument cluster could disrupt the Pass-Key anti-theft system, which can cause gauge failure and a no-start. If your car is part of this recall, the dealer fixes it for free.
• NHTSA complaints: 64 keyword-matched complaints for Cadillac Eldorado 1992–2002 (of 400 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-26; keywords: won't start, no start, battery, drain, dead, alarm, theft, starter). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In 1997 Cadillac Eldorado lights come on, but won't start on Car Talk, an owner said everything lit up but the car wouldn't start. Members asked whether it would start with a jump, whether it cranks or not, suggested trying neutral, and one said to check the positive battery cable for corrosion on GM cars of that era.
• In 1997 Cadillac Eldorado: trunk draining the battery? on Car Talk, an owner said the security system went off randomly, the dash clock went on and off, and a new battery went dead. The dealer thought the trunk, which didn't fully close, could be the cause. One member said disconnecting the trunk pull-down motor and lamp should rule out that area, another suggested the retained accessory power relay may not be shutting off, and another said an amp clamp and wiring diagram should find the circuit within about an hour.

Quick tip

Before paying for a guess, ask the shop to measure the drain and find the circuit. That's a one- or two-hour job, not a parts gamble.

Vehicle focus: 1992–2002 Cadillac Eldorado (Northstar V8).

Safety / mechanic note

Use proper jump-start order and keep clamps from touching. Verify with a mechanic.