FI / Sensors Harness vs Sensors

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Bob Weir
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FI / Sensors Harness vs Sensors

Post by Bob Weir » Thu Jul 17, 2014 12:14 am

FI / Sensors Harness vs Sensors

Next time you suspect a sensor or get a code, you might want to consider the wiring harness.

I opened 2 Fuel Injection / Sensor harnesses. Obviously the frayed wires in the “sensors” section are not going to make a proper connection, especially for the TPS [Throttle Position Sensor].

Around Sep 1995 Ford TSB instructs to use a new connector with “gold plated” clips. Part # E9RZ-9B989-C. Apparently Ford felt this a necessity for correct current flow.

Image

I also realized two differences in a harness from an 88 to another from an 89. The ground wiring is different and more obvious is the connectors to the main harness. The 88 has a male plug while the 89 has a female plug in FI / Sensors Harness. No mixing and matching here!
Image

Below is the 89 harness. It has a different Br splice for Water Temp Sensor with TPS.

Image

Both harnesses have the gray connector for 2 Bk wires on one end and 2 Br/Y wires on the other end.

Here’s the FI / Sensors Harness pin out:

Connector pin structure:
A row:
Br - 2, 3 & 5 Fuel Injectors
Br/Bk - 1, 4 & 6 Fuel Injectors
Bk - Idle Air Solenoid aka IAS.
Br/Y - IAS

B Row:
Br/Gr - Water Temperature Sensor [to EEC],
Br - Water Temperature Sensor [to EEC] and TPS pin 46 Signal Return [OEM splice in the harness]
Br/Gr - TPS pin 47 Throttle Position
Br/Bk Throttle Position Sensor aka TPS pin 26 VREF

Water Temperature Sender [to gauge] is a separate Br ground outside this harness.

What started my adventure into harness stripping…
In this case, my Scorpio developed a serious erratic idle and showed Code 63 [low voltage to TPS]. NOS Motorcraft TPS installed and code remained. Redid a few grounds as recommended my fellow Merkur owners that resulted in better performance, but Code 63 continued. I did all the workshop tests in “D” [Throttle Position Sensor] and “C” [Voltage Check]. I also have the “88” wiring schematic, Workshhop Manual as well as the “89” Elec & Vac Manual. Traced and jumped every wire I could. A few results were not to spec by the book. Ex 5.03 v vs 4.0 and others at 200k weren’t moving the ohm meter. I blamed misprint, inaccurate multimeter and even operator error and kept testing.

Your comments and especially corrections are appreciated. Thanks to everyone who helped me through this frustrating situation.
Last edited by Bob Weir on Sat Jul 26, 2014 10:45 am, edited 2 times in total.

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Bob Weir
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Re: FI / Sensors Harness vs Sensors

Post by Bob Weir » Tue Jul 22, 2014 11:05 am

Update

Reference Workshop Manual page 4-21 Electrical Schematic.

EEC pin 46 Brown wire is common to "6" sensors! HEGO, ECT, TPS, ACT, MAP and PFE.

In the first pik, the 2 Br wires are spliced together under black tape. This is OEM! The Br wire > connector > tape out under battery > EEC. I seriously suspect the TPS & ECT splice due to the engine's heat and movement. I suspect a short here could affect all the connected sensors.

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Re: FI / Sensors Harness vs Sensors

Post by Father Adam » Tue Jul 22, 2014 12:55 pm

I'd be interested to know what code reader you have Bob, I bought a Gunson one last year but it's for the later Ford models and so has a slightly different connector to mine (still 3 pin though).
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Ed Lijewski
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Re: FI / Sensors Harness vs Sensors

Post by Ed Lijewski » Tue Jul 22, 2014 1:46 pm

Descartes: "Cogito Ergo Sum"
Lijewski: "Sum Ergo Drive-O. Mucho!

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Re: FI / Sensors Harness vs Sensors

Post by Bob Weir » Tue Jul 22, 2014 2:08 pm

Father
I use a INNOVA #3145 for OBD 1. that displays the code #s. For Ford only 1981 - 1995. Cheep & simple to use. Comes with book of instructions and code # & their descriptions. I started with an Actron, but u have to count audible beeps = PIA.

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Re: FI / Sensors Harness vs Sensors

Post by Father Adam » Tue Jul 22, 2014 4:48 pm

This Gunson one I have is one that you have to count the number of flashes too, one with a display would make life easier for me.

Tell me though Bob, would this type of reader tell me which ABS sensor is kaput?

:cheers
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Re: FI / Sensors Harness vs Sensors

Post by Bob Weir » Wed Jul 23, 2014 7:45 am

The INNOVA #3145 for OBD 1 only does engine EEC management. Well worth its cost. My best guess on the is the Rotunda and ABS adapter as mentioned in the workshop manual. I often wanted to borrow one.

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Re: FI / Sensors Harness vs Sensors

Post by Father Adam » Wed Jul 23, 2014 8:19 am

Thank you Bob!

:cheers
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Re: FI / Sensors Harness vs Sensors

Post by Bob Weir » Wed Dec 13, 2017 9:24 pm

Since I'm not buying into Photobucket's extortion, I'm trying to replace some photos. Here's a few for this post.
FI Harness connector v1.jpg
FI Harness connector v1.jpg (48.4 KiB) Viewed 705 times
FI Harness connector v2.jpg
FI Harness connector v2.jpg (51.64 KiB) Viewed 705 times


"FI Harness ng r1.jpg" shows the terrible condition of the wires to the Throttle Position Sensor and other sensors.

NOTE This is the condition of the wires in a Scorpio. You can imagine what the heat of a Turbo could be doing to an XR's wiring. :shock:
FI Harness ng r1.jpg
FI Harness ng r1.jpg (46.73 KiB) Viewed 705 times

Nolan04
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Re: FI / Sensors Harness vs Sensors

Post by Nolan04 » Sat Feb 10, 2018 1:18 pm

Bob Weir wrote:
Thu Jul 17, 2014 12:14 am
FI / Sensors Harness vs Sensors

Next time you suspect a sensor or get a code, you might want to consider the wiring harness.

I opened 2 Fuel Injection / Sensor harnesses. Obviously the frayed wires in the “sensors” section are not going to make a proper connection, especially for the TPS [Throttle Position Sensor].

Around Sep 1995 Ford TSB instructs to use a new connector with “gold plated” clips. Part # E9RZ-9B989-C. Apparently Ford felt this a necessity for correct current flow.

Image

I also realized two differences in a harness from an 88 to another from an 89. The ground wiring is different and more obvious is the connectors to the main harness. The 88 has a male plug while the 89 has a female plug in FI / Sensors Harness. No mixing and matching here!
Image

Below is the 89 harness. It has a different Br splice for Water Temp Sensor with TPS.

Image

Both harnesses have the gray connector for 2 Bk wires on one end and 2 Br/Y wires on the other end.

Here’s the FI / Sensors Harness pin out:

Connector pin structure:
A row:
Br - 2, 3 & 5 Fuel Injectors
Br/Bk - 1, 4 & 6 Fuel Injectors
Bk - Idle Air Solenoid aka IAS.
Br/Y - IAS

B Row:
Br/Gr - Water Temperature Sensor [to EEC],
Br - Water Temperature Sensor [to EEC] and TPS pin 46 Signal Return [OEM splice in the harness]
Br/Gr - TPS pin 47 Throttle Position
Br/Bk Throttle Position Sensor aka TPS pin 26 VREF

Water Temperature Sender [to gauge] is a separate Br ground outside this harness.

What started my adventure into harness stripping…
In this case, my Scorpio developed a serious erratic idle and showed Code 63 [low voltage to TPS]. NOS Motorcraft TPS installed and code remained. Redid a few grounds as recommended obtenir crédit my fellow Merkur owners that resulted in better performance, but Code 63 continued. I did all the workshop tests in “D” [Throttle Position Sensor] and “C” [Voltage Check]. I also have the “88” wiring schematic, Workshhop Manual as well as the “89” Elec & Vac Manual. Traced and jumped every wire I could. A few results were not to spec by the book. Ex 5.03 v vs 4.0 and others at 200k weren’t moving the ohm meter. I blamed misprint, inaccurate multimeter and even operator error and kept testing.

Your comments and especially corrections are appreciated. Thanks to everyone who helped me through this frustrating situation.
OK, thank you very much for your share :)

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Bob Weir
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Re: FI / Sensors Harness vs Sensors

Post by Bob Weir » Sun Feb 11, 2018 1:04 pm

Welcome to the MCA
Introduce yourself to the members.
Here’s the link > http://forum.merkurclub.com/forum/viewforum.php?f=19
Also, Click on your username / User Control Panel / Profile =>

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