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Professor Quest
Joined: 09 Jul 2004
Posts: 5085
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Mon Mar 28, 2005 9:08 pm |
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STOP! This is just below your battery and it REALLY NEEDS to be CLEANED of any CORROSION!!
 THIS IS YOUR MAIN BODY GROUND, the ring eyelet behind it is the ECU & ISC/MPS (intake manifold) GROUND! ALL HELL BREAKS LOOSE IF YOU DO NOT SERVICE GROUND #11....which CONTINUES to become GROUND #3!!
Soaked in oil.... is not only bad for RUBBER, but it can INTERUPT a DESENT SIGNAL from a sensor. 
A SENSOR...sends a varible ground...but it NEEDS TO BE THERE FIRST!
A poor BODY/ENGINE GROUND would send false signals.
http://starquest.i-x.net/viewtopic.php?t=916
Because there are MANY sensors that are COOLANT TEMP RELATED: Failure to SPOT-CHECK FAN OPERATION= DISASTER!
http://starquest.i-x.net/viewtopic.php?t=1067
It's pretty hard to get ACCURATE temp gauges (uses VARIABLE GROUND RESISTANCE sent to gauges or ECU) if you have MORE RESISTANCE from contamination and OLD AGE....you'll send FALSE INFO!
You've got a 20 year old car.....and they are all down-wind of the battery which "weeps" battery fumes......just like the injector clips, "LOOK... BEFORE YOU LEAP!" 
Replacing JUST a TERMINAL? Contaminated COPPER WIRES is gonna travel thru several inches of wire!  
For the temp gauge. Single pin type $35. Two pin type $98.
Page 20 of "Introduction and Master Troubleshooting" in the 88 Starion service manual says they are AMERICAN PIPE THREADS.(NPT) "I" say they are American pipe threads. And after you chase the threads a little deeper........YOU'LL say they are American pipe threads.
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Last edited by Professor Quest on Thu Nov 05, 2009 9:37 pm; edited 19 times in total |
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:15 am |
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Yes, they ARE American pipe threads (NPT) just not tapped as deep.
Sender #1 Water temperture gauge. NOT A PIPE THREAD. M16 x 1.5
(also has a 2 pin type on some models)
Sender #2 EGR thermovalve 3/8" NPT pipe thread
Sender #3 CTS (ECU coolant temp sensor) 3/8" NPT pipe thread
Sender #4 A/C compressor over heat shut down switch 1/8" NPT pipe thread.
If EGR and A/C have been deleted, senders #2 & #4 can be eliminated. Hole #2 can be used for an aftermarket water temp sender.
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Last edited by JustPaus on Tue May 17, 2005 9:15 pm; edited 1 time in total |
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:16 am |
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HOW IT WORKS. This thermosensor sends a GROUND to the A/C compressor RELAY (located on the LH apron, one of the 4 that are ID) but will BREAK that GROUND if the thermosensor detects a OVER-HEATING ENGINE!
It merely STOPS the A/C CLUTCH (removes the positive currant via the relay) to assist cooling the engine.
All 4 relays are the same, so they may be switched to find a bad one.
Vehicles with intercooler.
1. Primary radiator fan A/C relay.
2. A/C compressor clutch relay.
3.Condensor fan/pusher fan motor relay. (pusher fan)
4. Secondary radiator fan A/C relay.
ID the relays:
2. Magnet clutch relay wire colors,
Green/white (from the "dual pressure switch")
Yellow/white (from the thermosensor above)
Black/white (positive currant sent to the a/c clutch)
Blue/red (from dedicated fuse #7)
Note the clutch itself has it's own ground wire.
You can use a TEST LIGHT to see if the thermosensor SPADE is
-GROUNDED- ALL THE TIME. If not -GROUNDED- (engine not over-heating)
that thermosensor is bad. Yes, you can full-time ground that yellow/white wire
but it's no longer a over-heat shut-down.
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:17 am |
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It provides the GROUND for the A/C compressor CLUTCH RELAY.
It is a THERMO SENSOR (means it has a transistor inside it) and when it
detects a OVERHEATED ENGINE....it shuts-down the GROUND
to the CLUTCH RELAY! to assist cooling the engine.
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:18 am |
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Single YELLOW WIRE with a WHITE STRIP.
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:18 am |
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If you have installed an aftermarket oil pressure gauge in the side of the block, you can use the the plug you removed to plug this hole IF you have deleted your A/C.
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:18 am |
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HOW IT WORKS! Testing your CTS. (coolant temp sensor) that "talks"
to your ECU to determine the AFR (air fuel ratio)
depending on the TEMP of your engine.
Also known as the "CTS" $45-$80. (depends on the quailty )
Gotta bad/corroded connector? Speaker connectors and few inches of good wires can fix that! Note it ALSO has a RELEASE LEVER!
THE CONFUSION IT CREATES: Your ECI/COMPUTER sends a -GROUND- to the CTS (top of the "T") then sends it BACK to the ECI/COMPUTER by *INCREASING* THE GROUND AS THE MOTOR WARMS!
MORE CONFUSION... if somebody HACKED this harness!
You'll have SEVERAL YELLOW/GREEN wires in that harness...TOO many of them! (some are not used) Andddd you've got a YELLOW/BLUE in there tooo.  (hard to tell the differance...look closer!) and get this....IT CHANGES COLORS MID-HARNESS!
Your test, ignition "on":
GROUND...for a breif moment, a YELLOW/GREEN wire as you OBSERVE the TEMP GAUGE in your dash. It should MAX-OUT the temp gauge...so MARK IT for that use!
NEXT...test another YELLOW/GREEN and WATCH THE GAUGE! Cause TWO OF THEM are ONE-IN-THE-SAME! (but you'll only need one)
NO REACTION (to the gauge) = CTS signal wire. Pin #6 INTO the ECI/computer...the feedback ground signal. ORRRRR it could be the yellow/green that tells the A/T relay it is warm enough to use overdrive.
If you'll CONTINUITY TEST each yellow/green with pin #6 at ECU harness at one end (blue connector)...you would *KNOW* that is a CTS signal wire.
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:19 am |
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The BLACK WIRE IS: The GROUND SORCE... that comes FROM THE ECU (your computer) then is REPEATED-BACK to the ECU....using the YELLOW/GREEN WIRE so the ECU knows how COLD/WARM the engine is...so it can ALTER...CHANGE the TIME PERIOD that OPENS THE INJECTORS! (cold engines need to be a lil' richer)
Note terminals are not the same! You need a SOLID, CLEAN, TIGHT terminal to send a GOOD, RESISTANCE FREE CONNECTION!!
This signal is sent to your COMPUTER!!
Two wire harness. YELLOW with a GREEN STRIP and BLACK. Shaped like a "T"......the BLACK wire would go to the TOP of the "T". Coverd with a rubber boot from the factory.....which can HIDE A PROBLEM!
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:19 am |
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CTS (coolant temperture sensor)
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:20 am |
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Engine coolant sensor/sender for the dash ENGINE TEMP gauge...
...looks SIMULAR to a CTS!!
Single pin type $35. Two pin type $98.
The lower part of the two pin "T" sends a GROUND to the OVERDRIVE RELAY after the engine warms up. (only has a use with A/T cars)
If *YOUR* car is a 5 speed...that has a TWO PIN...and is plugged-in,
the YELLOW/GREEN is a DEAD-END WIRE....DOES ZIP...NADDA..NOTHING!
SUPER NOTE: Yellow/blue & yellow/green...FLIP-FLOP those colors at a harness JUNCTION under your dash...above the HVAC unit.
True...if you have an 87, and you change out the harness to a 88/89 harness...that JUNCTION is differant. You'll want that half of that harness too, or BUILD your own connector....keeping inmind that the colors changed. In other words....*TEST* each wire to select the RIGHT wire that reports to your TEMP GAUGE.
Starquest with a A/T transmission using the 2 pin connector.
The 2 pin SENSOR is known to malfunction...and it might shift up-in & out
of overdrive but the OTHER pin reports ENGINE TEMP just fine.
YOU CAN...give that YELLOW/GREEN wire a FULL TIME GROUND and you'll OVERDRIVE command at the switch on your shifter handle.
More on page #3
KNOW THIS! If your car had a 5 speed....that yellow/green wire ain't doing dick! 
It won't even HAVE the A/T relay (located by your left foot well in A/T cars)
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:20 am |
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KNOW THIS! Vol 2 of the FSM (meters & gauges) says:
"yellow/green" sends the signal (87 vol 2) yet "yellow/blue" sends the signal (89 vol 2) Btw...they only show ONE wire attached at all!
SUPER NOTE! Early cars had BOTH a single pin connector...
and a TWO pin connector...that was TAPPED INSIDE the harness
cause it wasn't used until about 88s!
YELLOW/BLUE is the SENDER to the DASH TEMP GAUGE.
YELLOW/GREEN sends a GROUND to permitt the A/T to use OVERDRIVE,
(yes...it is known to fail, and yes...a COLD ENGINE don't like O.D.)
Yellow with a blue strip and yellow with a green strip. Note the green lead is NOT all the way on. Improper/corroded connections can give false readings.
Failure to CLEAN or REPLACE DIRTY, CORRODED TERMINALS SENDS BAD SIGNALS or NO SIGNAL AT ALL!! If it has a A/T, and it jumps in & out of OD...more than likely this sender is bad.
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:20 am |
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NOTE: This is NOT A TAPPERD PIPE THREAD. It is a M16 x 1.0. It seals with sealant on the threads. The red surface is where it bottoms out in the manifold.
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:21 am |
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Like I said, dirty and corroded connectors could be the reason you are getting bad signals from the sensors/senders.
A can of carb cleaner, (leaves behind a film/residue )
....or merely a bucket of cleaning solvent can make them as clean as new.....BUT FOLLOW WITH TERMINAL CLEANER!! There are WARNINGS ABOUT THIS in the front of a Hayne's Manual.
Also.....any MALE CONNECTOR needs to be pinched TIGHT by the female side. You can use a pair of pliers to CLOSE UP THE FEMALE SIDE. Just don't get stupid and close it so far you can no longer get the male end in.
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:21 am |
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 2:21 am |
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 9:16 pm |
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 9:16 pm |
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Sensor #1: KNOCK SENSOR
Sender #2: AFTERMARKET ELECTRICAL OIL PRESSURE SENDER W/ low oil pressure lead for a warning light. (VDO)
Sender #3: Factory oil pressure sending unit
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 9:17 pm |
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You can switch out the oil pressure sending unit to the Carquest PS-192, but again the threads in the oil adapter are not tapped as deep so the new sender will only go in a couple of threads. If you don't chase the threads deeper.......you'll probably crack the ALUMINUM adapter when you try to force it in deep enough.
The alternative: use this adapter to adapt 1/8" x28 to 1/8" x27!
$23
The brass Sunpro adapter is STRAIGHT THREAD.....NOT TAPPERD!!
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 9:17 pm |
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 9:17 pm |
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DO NOT BUY THESE!!
Sold by Auto Zone, the CP7573 is said to be the right adapter to convert METRIC to AMERICAN threads.
In the first place, this engine does not have a METRIC fitting for the oil pressure switch at ANY location.
Secondly, although the package does say it converts Metric threads, the kit also contains a 1/8-28 BSP thread to a 1/8" NPT thread. This is the one that you will find DOES START into your block. But it will only go in about 3 or 4 threads before it becomes tight. It's CLOSE......BUT NO BANANA! 
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 9:18 pm |
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Using a GOOD, HARDEND 5mm Allen socket drive and a breaker-bar attempt to remove the plug. It will require some torque.......BUT DO NOT STRIP IT! Back-off if it FEELS like it is going to STRIP.
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 9:18 pm |
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 9:19 pm |
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 9:19 pm |
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That's a 1/8" BSP (straight thread) not a 1/8" NPT.......which is what the block is. This adapter SPELLS DISASTER! DO NOT USE IT! |
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JustPaus
Joined: 06 Oct 2004
Posts: 1656
Location: Gilbert, Arizona
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Tue May 17, 2005 9:20 pm |
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