Diagnosing P1280 in a Late 99

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Feb 14, 2023 | 11:53 AM

cfpinz

Thread Starter

Mountain Pass

Joined: Aug 2006

Posts: 196

Likes: 34

From: Virginia

Diagnosing P1280 in a Late 99

One of our farm trucks is a late 99 7.3 with 300k or so on it, truck cut off while idling the other day while I was away from it so I'm not sure how it sounded when it died. Started back up immediately but has had SES light on since then. Scanned with AE last night, and got the P1280 ICP circuit low code. Could not erase code, buzz test sounded normal. ICP looks fairly new, harness is decent enough looking and IPR looks pretty old.

All of our other 7.3 trucks are 1997 and prior, so I'm not overly familiar with this model. Is there a diagnostic procedure for P1280 in these trucks so I'm not tossing parts at it unnecessarily?

Thanks.

Feb 14, 2023 | 03:14 PM

knottyrope

Lead Driver

Joined: Apr 2016

Posts: 7,206

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From: Bahstun

did you check the engine oil level?
is IPR nut on tight?

Feb 15, 2023 | 07:05 AM

cfpinz

Thread Starter

Mountain Pass

Joined: Aug 2006

Posts: 196

Likes: 34

From: Virginia

Quote:

Originally Posted by knottyrope

did you check the engine oil level?
is IPR nut on tight?

Yes and yes.

The ICP was showing 724 psi at idle, is that in the expected range?

Feb 15, 2023 | 07:33 AM

FordTruckNoob

FTE Chapter Leader

Joined: Jan 2005

Posts: 13,113

Likes: 4,717

From: Henderson, NV

DC Pinpoint Tests attached.

Attached Images

DC Pinpoint Tests.pdf (391.4 KB, 41 views)

Feb 15, 2023 | 07:57 AM

Kwikkordead

Fleet Owner

Joined: Jun 2004

Posts: 25,090

Likes: 1,112

From: Rio Rico, AZ.

Given the age of these trucks now if there's a low circuit code, the first thing on my list is new connectors for the offending circuit. Then take it from there.

Feb 15, 2023 | 10:07 AM

cfpinz

Thread Starter

Mountain Pass

Joined: Aug 2006

Posts: 196

Likes: 34

From: Virginia

Thank you both, I appreciate it!

Feb 15, 2023 | 01:20 PM

Dmco

Tuned

Joined: Nov 2020

Posts: 403

Likes: 171

From: Greenville, SC

I had a P1280 pop up several months after installing a convincing counterfeit ICP sensor from Scamazon. It wasn’t until comparing a genuine OEM Motorcraft sensor from the dealer parts counter that I could notice very subtle differences in the packaging. I have had no issues since installing the legit sensor. May not apply to your situation but food for thought!

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Feb 27, 2023 | 09:38 AM

cfpinz

Thread Starter

Mountain Pass

Joined: Aug 2006

Posts: 196

Likes: 34

From: Virginia

Just to update thread, I hooked AE to truck and it showed 0V coming from the ICP while running. Installed new Motorcraft ICP from Diesel O-rings and it's up and running again, no SES light.

Thanks to all for the help.