

| Subject: | Re: Only 5V at Temp II sensor? |
| From: | David Beierl |
| Date: | Sat, 27 May 2017 17:31:24 -0400 |
Those connectors are readily available at the FLAPS -- look in the H.E.L.P. section for Bosch-style fuel injection connector pigtails. Probably wrong color, but otherwise the same. Yrs, d On Sat, May 27, 2017 at 5:15 PM, George Gaudette <gcgaudette@gmail.com> wrote: > I failed to reply all -- sorry to David for the double post. > > Also, I should add that the 67 ohms resistor is supposed to approximate the > resistance produced when the sensor senses coolant at normal operating > temperatures. More or less. > > Now once more, with feeling... > > Once Mark pointed out my mistake I disconnected the **correct** sender and > found the positive wire broken at the spade, with lots of corrosion. With > the wire stripped a little I got 9V to the brown wire's spade (tough to get > the test lead to touch it well though) and 10V when grounding to a nearby > ground strap instead. > > I hooked up the "67 ohms" resistor that I fashioned and the temp needle > moved for the first time in a long time -- slightly above dead center over > the blinkenlight, which I consider normal. > > Now I've gotta figure out how to get that orphaned spade out of the > connector, or replace the connector. The back of the spade is completely > corroded away. > > Anyhow the problem is isolated, so I think I'm well on my way. > > Thanks again. > > On Sat, May 27, 2017 at 5:12 PM, George Gaudette <gcgaudette@gmail.com> > wrote: > > > Thanks David! > > > > Once Mark pointed out my mistake I disconnected the **correct** sender > and > > found the positive wire broken at the spade, with lots of corrosion. > With > > the wire stripped a little I got 9V to the brown wire's spade (tough to > get > > the test lead to touch it well though) and 10V when grounding to a nearby > > ground strap instead. > > > > I hooked up the "67 ohms" resistor that I fashioned and the temp needle > > moved for the first time in a long time -- slightly above dead center > over > > the blinkenlight, which I consider normal. > > > > Now I've gotta figure out how to get that orphaned spade out of the > > connector, or replace the connector. The back of the spade is completely > > corroded away. > > > > Anyhow the problem is isolated, so I think I'm well on my way. > > > > Thanks again. > > > > -George > > > > On Sat, May 27, 2017 at 5:03 PM, David Beierl <dbeierl@attglobal.net> > > wrote: > > > >> > >> > >> On Sat, May 27, 2017 at 2:45 PM, George Gaudette <gcgaudette@gmail.com> > >> wrote: > >> > >>> Hi Volks, > >>> > >>> '90 water-cooled automatic camper here. > >>> > >> > >> Thank you. :) > >> > >>> > >>> My coolant temp needle stopped moving entirely some time ago. The > >>> coolant > >>> blinky light works normally (blinks initially on startup then goes out, > >>> and > >>> has recently blinked for low coolant level). > >>> > >> > >> Good. Gauge doesn't have leaky timing cap, and coolant level controller > >> is successfully simulating overheat in short pulses that activate the > >> blinker but don't materially affect the gauge itself. > >> > >>> > >>> ...which is to say I hoped to validate that the temp gauge is in > working > >>> order (including the wiring to it). > >>> > >>> The first thing to do was to check that there is 10V across those > wires. > >>> Instead I found there was about 4.9V. I tried with the negative lead > >>> touching a ground point instead of the brown wire, and got 5.3V. > >>> > >> > >> The ECU supplies five volts to Temp-II through an ?8132 ohm? resistor, > >> creating a voltage divider with the variable resistance of the Temp-II > >> sender. This however has nought to do wi' t'gauge -- the problem there > is > >> that one of the fly rods has outta skew on t'treadle. Or more likely > that > >> the sender or connector is open, of course. It's the black one around > the > >> corner from the blue Temp-II sender which is concerned strictly with > engine > >> operation. 265 ohms to ground should give you the bottom mark, 35 ohms > the > >> beginning of overheat zone and blinking light (light threshold is > around 42 > >> ohms IIRC). Grounding the sender lead should make the gauge go up like > a > >> slow rocket, and if you leave it connected, start smelling hot in a > minute > >> or two. No action means either a wiring problem between engine bay and > >> gauge (but not the panel connector or panel wiring since the low coolant > >> warning functions) or -- very very unlikely, the gauge heater has gone > open > >> or the needle suspension has failed. > >> > >> Yrs, > >> d > >> > > > > >
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