[Vwdiesel] An off-topic, but Diesel question (fwd)

[Frank G. Pival]

My ignition switch also stopped allowing me to start my 96 Passat TDI so 
I installed a momentary push button on the dash..these creative 
go-arounds ARE great anti-theft deterrents.

On 6/20/2012 5:35 AM, Val Christian wrote:
> FWIW, in my second 77 Rabbit, I simply wired the GP relay to a fog light switch
> which served me fine for years.  Back then relays were problems.
>
> Sometimes wish I still had a "fog light-glow" switch.  BTW, a great anti-theft
> device in the winter.
>
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> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> Also, not familiar with that model/engine myself.
>
> But I did play around with some glow plug relays from by various VW diesels with a tester
> I built at one time.  What I found was that some of the various GP relay brands/designs
> were very "robust" and others were very "sensitive" to the various inputs.  What I mean is
> that the "robust" designs (like the real Bosch relays) would "do the right thing"
> regardless of the inputs.  So if the temp sender ran say from 1000 ohms cold and 100 ohms
> hot.  Both the robust and sensitive relays would work properly given those input
> resistance ranges.  But if you get a little out of that range, especially like an open
> circuit, the robust relay design would just call that "really cold" and put the glow LED
> on for the longest programmed time.  But the sensitive relays would do all sorts of
> strange things, like not turn on, turn on and off at random, etc.  In my case, I tracked
> down my problem to a broken connector terminal in the GP relay socket.  When you plugged
> the relay in, the temp. sender pin on the relay would push the terminal in the socket out
> of the way, creaking an open circuit.  SO it turns out all the "bad" relays I had
> accumulated were all "good" and I had a bad socket.
>
> Anyway, if that engine uses a glow plug relay with coolant temp sender (similar to VW),
> then I would check out that temp sender circuit, making sure the sender is putting out a
> proper signal, that the wiring from the sender to the relay is good and if all else is OK,
> maybe the relay (or socket) is acting up.
>
>
> On 6/19/2012 10:45 PM, Shalyn Shourds wrote:
>> Sorry for the lack of VW content, but I don't know a better group of Diesel mechanics.  Brother-in-law has a 92 Ford 250, about a quarter million on the clock.  He finally got around to changing the glow plugs after a couple years of ether starts.  Now it starts fine cold.  It, however, won't start if he warms it up then lets it sit for an hour turned off.  I didn't know what to tell him because if it starts cold, everything mechanical should be working.  My only thought was that maybe the glow plug coolant temp sensor was saying "don't glow" erroneously when it was a little warm, but not warm enough to start unaided.  I know very little about those engines, though.
>>
>> Thanks in advance,
>>
>> -Shalyn
>>
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