Why do the lights on my MG Midget dim and brighten, and why do the electrics come and go?

Short answer: Pulsing lights on a Midget usually point to a bad ground strap between the engine and the body. Clean and tighten both ends or replace it. If the horn, signals or other circuits come and go, clean the Lucas fuse box, pinch the clips so the fuses grip, and go over the connectors.

Symptom: The headlights and dash lights pulse dim and bright, or the horn and turn signals work only some of the time.

What to check first

1. Find the braided ground strap from the engine to the body and check both ends.
2. Check the battery cable ends.
3. Pull each fuse, clean the clips and pinch them tight.
4. Check charging voltage at the battery with the engine running.
5. Wiggle connectors on the problem circuit while it's on.

Likely causes

1. Bad engine-to-body ground strap. A braided strap joins the engine to the body. If it's loose or corroded, the lights and the charging system see different voltages, so the lights pulse.
2. Lucas fuse box contacts. The fuse holders lose their grip and corrode, so circuits drop in and out.
3. Loose or corroded connections. Old bullet connectors and switches cause intermittent horns, signals and lights.

What it usually costs

Owners in these threads didn't post prices.

Is it safe to keep driving?

Flickering headlights and dead turn signals are a night-driving and signaling risk. Fix them before driving at night.

DIY or shop?

All DIY with basic tools and a meter.

Recalls, bulletins and complaints in plain words

• Related recalls: NHTSA lists a headlight recall (72V208000) for some 1972 MG cars; NHTSA's summary text is blank, so check the details. Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• Plain words: The complaint count below shows how often owners reported problems that mention these words to NHTSA. A count is not proof of a defect.
• NHTSA complaints: 0 keyword-matched complaints for MG Midget 1966–1979 (of 0 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-30; keywords: light, electrical, wiring, lamp, horn, engine) (NHTSA returned no data for 16 model-year queries). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In 1977 MG Midget bright/dim headlamps on Car Talk, a 1977 Midget's headlights and dash lights kept dimming and brightening, at idle and at speed. A member explained the ground strap between engine and body (or firewall): if it's bad, the engine ground 'floats' compared to the body and the lights see changing voltage.
• In 1977 MG Midget on Car Talk, a 1977 Midget owner's turn signals and horn worked only some of the time. Members said to go over every connection for looseness and corrosion and to clean the old Lucas fuse box slots and pinch the clips so the fuses grip again.

Quick tip

Before you blame Lucas, clean the grounds. A fresh ground strap is the cheapest fix on these cars.

Vehicle focus: MG Midget, 1966-1979.

Safety / mechanic note

Lighting and signals are safety items. Verify with a mechanic.