Ah, someone reminded me tonight that you're supposed to cross the test leads first, then subtract whatever reading comes up from the test reading? That was missing from my extensive (cough) knowledge in this area.

Mine reads .3 across the leads, so therefore the four plugs actually measured about .8 ohms.

Yes, the harness was unplugged.

Question: I understand this test is supposed to be done on 'cold' plugs. The plugs were cold, as in not having been activated that day, but the block heater was plugged in. Would the slight amount of heat reaching the GPs alter the readings?

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I doubt it. I'd swap out that one plug.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Hi Z The resistance in the plugs goes up as they heat up. The difference in resistance between 30-100 deg is negligible

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85 Merc 300D - Unwinding 31 years of wear
86 VW TD
Mahindra Diesel
Iseki Diesel

In 2007 I didn't own a diesel.

For sure. I asked about the heater only because as I understand it .8 is still considered high for brand new GPs (well, depending on whose thread you read, anyway).

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

The meter is usually adjusted to bring this reading to zero before you measure.

Of course, if you have one of those newfangled digital gizmos.............

We've been in a cold snap and I have no garage, so I have not been able to see if replacing my single bad GP will have any bearing on my problems starting at under -10 C.

The weather 'warmed' to -10 C today on the nose. I did not use the block heater last night.

Sure enough, when I cranked it this morning I was getting fuel but no evidence of any glow. (Glow light illuminates and I can hear the relay click.)

I pulled the cap off the relay and unplugged the big connector. When I turned the key to the glow position again and tested the male pins for voltage I got nothing.

Turned the key off then on again and tried for voltage at the top right receptor on the small plug (I wasn't thinking on my feet when I switched off the key). Ok. Immediately plugged both connectors back in and waited to hear the relay click off.

Turned the key and the car started.

Now I am wondering if the GP that OHM'd out way high is just a red herring and I maybe have a temp-dependent problem with either the relay or the ignition switch.

I may try again later (still pretty cold working out there, with the wind chill factor).

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22