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Low voltage to glow plugs

Posted: Sun Jun 15, 2025 4:29 pm
by BigFreda
Hello,

Had some issues starting my bongo, was running abit rough. Changed the glow plugs and buzz bar as I realised it was shorting and had a large bare patch on the underside. Using a multimeter I realised that it's only reading 9V coming through to the glow plugs before returning to zero after the click. Is this a glow plug relay issue, fusible link or both? I have checked the battery and it's absolutely fine

Any advice welcome

Re: Low voltage to glow plugs

Posted: Sun Jun 15, 2025 9:37 pm
by g8dhe
The Glow plugs do normally operate at less than 12v and frequently rated at around 11v I have noticed, however the voltage will normally increase as they get hot and the current they draw falls off. A common glowplug is the NGK-701J variety;

https://www.sparkplugs.co.uk/ngk-glow-p ... 01j-5116-3 for the specification

So dropping as low as 9v would tend to indicate a problem, either the battery & connections or dirty relay contacts etc.