[Vwdiesel] Glow Plug Relay troubles

[Roger Brown]

David Cook wrote:
> I installed my glow plugs this afternoon, as well as
> finally getting the cold start handle in!  Woo Hoo,
> the conversion is finally complete after two plus
> years!
> 
> Anyway, the reason the GPs burned out is that the
> relay will very quickly trigger on and off, causing
> the indicator light to flash and the GPs to get power
> and have it cut off very quickly over and over.  It
> happens so fast it sounds like a cicadia is under the
> dash buzzing or something.
> 
> My theory on why this was happening is that the
> wiretap I did to get the signal to turn the plugs on
> from the ignition switch was bad.  Today, I redid that
> connection and it still did it once while driving.
> 
> I also noticed that sometimes when the car is started,
> the indicator light will flash, though I can't hear or
> feel the relay clicking.  Revving it so the alternator
> will start usually makes that stop, but not every
> time.
> 
> It does it with two different relays, one VW and one
> aftermarket.
> 
> Any ideas on what to investigate now? 

Any of the connections to the relay being loose/intermittent can cause that.  I found the T 
(temperature sender) input to be trouble prone.  I had a crack in the plastic relay socket near the 
T terminal and it let the metal contact move as the relay was inserted:
	http://www.4crawler.com/Diesel/GlowPlug.shtml
I found the Bosch relays to be the most robust.

-- 
    Roger