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Checking Fuel Injector Resistance - 1990-1996 Q45


No guarantees are made on the results, and anything you do yourself is at your own risk.

Checking Fuel Injector Resistance
By Wes Stinson 

Update: On 1990-1994 Q45s, you should close all doors, remove the key, and make sure nothing is plugged into any 12v sockets to get an accurate reading. On 1995 and later Q45s, you may need to turn the key to "on" because the injectors are on switched power.
-JG

Normally you want to check the injector resistance when the plenum is off.  However, when you are diagnosing a possible injector failure this isnít always recommended.

Please note the resistance when measured through the harness (as described in this article) is not the most accurate (within maybe 0.1 ohms) but enough to tell if the injector is bad or out of spec. 

The correct range is 10-14 ohms.
 

You must first unplug the injector harness.  It is shown here:

The blue arrow points to the correct harness connector.  Depending if you have a California or Federal model, you may not have the same amount of connectors so the picture wont be the same, but it should be close enough.

What you do is unhook the connector.  Once you do that, you want to test the side with the pins.  Attach the POSITIVE probe of your meter to the positive post on the battery.  Then, take the negative probe and put it on the individual pins.

The pin outís as they are on the injector harness as you face it

1-7-6-4
8-3-5-2

See the two photos below contributed kindly by Mike Goodwin:


From the top of the engine, here is a layout of the injectors.  Its approximate, just to give you an idea:


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