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Rear ABS Illuminates -- will not produce fault code at test

Kaajot

Micro Machine Manager
Ok, so interesting update regarding ABS and my tow control/brake control.

Connected to a 2000 lb 10K car hauler 18' trailer. We put about 65-70 solar panels on two stacks so that was about 2K more lbs.

Well, I noticed I don't get a P.L. as frequently, but I still do. However once I get moving the n.c/c is showing (c.) for connected.

Now for the interesting part. The ABS does not ever illuminate. It doesn't get triggered.

Unplug the trailer and get above 35 mph, it'll flash the ABS light.

So I think the short/ground (P.L.) is linked to the trailer 7-pin connected and with the ABS somehow (because the ABS won't go off with the trailer connected).

Anyone smart enough on why this is going on? I have been trying to figure out for awhile regarding what is still shorting to cause that P.L. indication on the brake control since all of my trailer connections function as-intended (Brake control, lights, directional, etc).
 

Kaajot

Micro Machine Manager
Slowly getting there....

So, it took awhile longer to get to this, but the old one is off. Have pictures, had lots of corrosion including some at the pins. I cleaned out the pig tail on the vehicle side of the harness, but did have one mishap which leaves me stranded until Amazon rescues me with new nickel-copper brake line and fitting, flair tool, cutting tool (I probably could have used my plumber stuff, but wanted to put one with the flairing tool), and a bender.

I think I could use the original steel line where the aft 9/16 fitting goes on the 3/16 line (rear line on ABS Control Unit), but the tool cost a lot more and the rust resistance seemed like a good trade-off with the nickel-copper since I don't off-road and should not be slamming sticks and stones against the line all day long. The forward steel line tube didn't brake on the smaller fitting, although it did round off on one corner. I'm going to just rebuild a line and slam it through there I hope since most tools (unless I buy a $200 flairing tool) have a harder time making a decent steel flair and they required a vice on a bench, which I don't have in my driveway.

Will post photos tonight and will turn on electronics to see if the ground-out fault goes away with the new connection (shows on my brake control there is a ground somewhere).

Engine is finally getting into the shop on Tuesday for warranty work also, so I'm hustling to get all the little deferred maintenance done so they are working with the better parts and not attributing gremlins to those things (pending installer installation errors are not present).
 

Kaajot

Micro Machine Manager
Ok, so the ABS Control Unit is as buttoned up as possible without the new brake line manufactured to go from the master cylinder to it (service line/input).

For this reason, I'm obviously not stomping on the pedal right now. No fluid came out of the outflow line, so my guess is (and my brakes and front suspension has been evident of this) that I have been driving old man style and relying on front brakes only the entire time. I do have the front tires up on ramps and wheels chocked on rear, so maybe that helped keep the fluid there, which so minimize bleeding (air input). That line is sealed again, so no extra air should go in.

I tested the vehicle first with the pigtail disconnected. ABS light came on immediately and remained on.

I plugged in the ABS Control Unit and the light did not come on. Once I have the line remanufactured/flaired and installed I can bleed this thing and see if the ABS light comes on after 35 mph or if it starts handling like a truck with four good braking wheels instead of two doing all the heavy lifting on the front end.

I'm just linking a folder with the 9 pictures off my Google Drive, will select which ones to upload here later.

You can see the before and after plus a good shot of the corroded plug off the ABS Control Unit and the pig-tail was a little gunked up too, used a micro flathead and cleaned it up a bit. Need to go back later and put some dia grease in for longevity, but I'll be under there a few more times so it'll get done. I also believe most of my brake lines at the front are looking rusty and if this fabrication goes well I'll probably work on replacing the others later this Fall.

Here's the ABS Control Unit Install photos and you can clearly see the broken brake line fitting that connects to the master cylinder. I've taken two pictures of the fitting that snapped off too. I should have double-wrenched that one now that I see it's a smaller line fitting off the 3/16 going to the larger fitting. Someone improvised here or Ford was dumb in general. The larger fitting that connects into the ABS Control Unit point may be able to be eliminated with the new brake line kit I have coming -- nickel-copper line with fittings 3/16 line and I am pretty sure there may be a direct 3/16 fitting of the larger size for me to simply add to the new line, flair, and install without creating the nesting-doll fitment from the original manufacturer, unless there is a good reason for it! I can't think of other than to assure an amateur mechanic (me) learns the hard way.

https://drive.google.com/drive/folders/1MVK-LXxrXOXB21Qs3ADwuMPI_Lbq9fJ8?usp=sharing

Oh!

There is a plug just hanging forward of the ABS Control Unit -- wiring harness plug. It's not doing anything, a little covered in oil, needs to be cleaned. What is it? It's in that folder, but here's a direct link to that picture.

https://drive.google.com/file/d/13uTvo9X2SG1OTxilPw1wy1bRxF9U-CKx/view?usp=sharing

Should I just clean it up, put a baggie around it, etc and zip tie or is this something that should have been connected and was not?
 
Last edited:

Blue-Truck-Nut97

crank polisher
551
18
Read through your posts kinda quick, not entirely sure of your situation, but a couple things I wanted to point out, on your trailer connection problems, check the trailer connection plug, ( male and female) I've had them fill up with water and short out, causing a similar problem.

Second, I hope you bought a double flare tool, single flares tend to break on brake applications, in my experience anyway.
Second and a half, I personally don't like copper line for brake lines, it might work, but vibration will bust the flares off sooner or later. The only time I have had any luck with copper line is when using compression fittings.

Glad you are making progress!

Sent from my E6810 using Tapatalk
 

Kaajot

Micro Machine Manager
Read through your posts kinda quick, not entirely sure of your situation, but a couple things I wanted to point out, on your trailer connection problems, check the trailer connection plug, ( male and female) I've had them fill up with water and short out, causing a similar problem.

Second, I hope you bought a double flare tool, single flares tend to break on brake applications, in my experience anyway.
Second and a half, I personally don't like copper line for brake lines, it might work, but vibration will bust the flares off sooner or later. The only time I have had any luck with copper line is when using compression fittings.

Glad you are making progress!

Thanks! Hoping to be in Michigan with this Truck and towing a gutted Sunline camper near the end of August.

Yeah, I did my research. It's a double-flare, but the cheaper tools don't handle stainless steel very well. I saw a third option, there was galvanized steel, unsure which was better, but I don't think galvanized qualifies as "soft steel." The $200 tool is possible to buy, but I'd need to get a bench vice and manufacture a bench on my deck or something to make it work.

I was worried about the nickel-copper not holding up. Well, the good thing is I'll have spare parts, a bender, etc all under the bench seat and can repair the line again should it bust the flares on the road at some point on this line. If I go to rebuild other lines after this experience, I'll invest in the bench tool ($180) and a vice ($50 HF one) but do wonder if Stainless or Galvanized Steel is the best line.

Oh yeah, my trailer connections are very well secured without water, have covers and a flip-down license plate for added protection and "hiding" of the trailer connections 7 and 4 way. It's definitely not the short. The short has been connected to the ABS I believe for a very long time and I didn't realize it. My ABS used to come on when I knew nothing about automobiles and just started doing brakes, rotors, and calipers for the first time. I won't know til I drive with functioning ABS, but I've checked nearly all wires and the brake control keeps reading it and the ABS Control Module fails to communicate, so I think the commonality was a short between these systems and their wiring. Again, unsure how I could have let it go this long but my ABS probably was failing since 2011 or 2012 and I blamed the Tornado, the 12 pt buck, the bad transmission for my need to drive slow. It progressively got worse.

We'll see how the ABS performs once I get the line manufactured and installed.

You know, I found an entire 1992 F-150 steel brake line OEM kit for sale for about $200. It had all the main lines. Maybe I should just go for that later if I decide to redo all the lines.

If you can take a look at the broken fitting picture, I could probably get the 3/16 line out of those fittings, cut off the frayed edge, and re-flair the existing steel line if the tool is strong enough against the old steel. I might try that -- will practice a flair on the copper and then give reattaching the original fitting. Still need everything but the NiCo line to do that anyway, so will happen Friday when Amazon delivers.

The other picture of interest is that random connector picture. I found it forward of the ABS Control Unit, just dangling with oil. Unsure what its purpose is, but it is saturated with oil. No electronics cleaning fluid on hand, so will have to wait for the truck to work. Amazon was backordered on any of those til August 25th, faster to drive into town and get a can Friday evening.
 

Fellro

Moderator
Staff member
I bought this tool a few months ago as the standard flare tools suck for tight areas on repairs. This is only good for 3/16" lines, but has worked amazing. You can use this pretty much blind and get a nice double flare.

Works great on factory steel lines, and also recently tried galvanized steel as the green coated lines were rotting out way too fast. This tool worked easily and didn't chew up the line like the cheap flare tools do. Don't know if it would do good on stainless.
72851535_L_c732b398-2adf-4f18-872e-d0836d575bd1.webp

https://www.speedwaymotors.com/Tita...GbM77x3UioEMm87H4Q5B08o1mX7M6ZsRoCWaQQAvD_BwE
 

Kaajot

Micro Machine Manager
I bought this tool a few months ago as the standard flare tools suck for tight areas on repairs. This is only good for 3/16" lines, but has worked amazing. You can use this pretty much blind and get a nice double flare.

Works great on factory steel lines, and also recently tried galvanized steel as the green coated lines were rotting out way too fast. This tool worked easily and didn't chew up the line like the cheap flare tools do. Don't know if it would do good on stainless.

Yeeehaw. :)

Behold my order yesterday after some research. It was this or a $200 tool which was the bees knees but needed a vice, wasn't really a hand tool, etc.

So the galvanized steel is a good option then if I manufacture the lines with this tool, adding strength and rust protection. Good stuff.

The other option if I wind up doing all the brake lines say, this Fall or next Spring is stainless steel premanufactured.

I could buy the tool and vice for $230, or save the labor and guess work with a $230 kit (shipping, etc brings it up to about the same). Only other vehicle I could see myself manufacturing lines for is the 1985 F-700, but I do repair refrigerators occasionally and being able to manufacture a line might come in handy, but it's not something I've had to do yet. I could see myself possibly bending lines for an aquaponics system using some weird thermodynamic system I've not developed yet or building a hippy outdoor hot tub with bent tubing as well. So maybe? But I did invest in the good bending tool, so I have that capability. Flairing might be useful to make secure connections without brazing.

https://www.inlinetube.com/products...tm_source=google&utm_campaign=Google Shopping
 

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Kaajot

Micro Machine Manager
So, right meow the existing stainless steel line has been repaired. Keith came over and helped me flair the original line with his tool (I couldn't get ahold of him yesterday so went all-in on tools on amazon, hah!). It's holding fluid, springs on drums are flexing, got a bunch of crud out the bleeder ports on the wheels so that was good. All new brake fluid (dot 3) installed, filled, bled.

Gonna drive to the farm in a bit, will get up to 45-55 mph and see if the ABS stays functional. Still a short, thinking I won't be able to pull codes from the ABS Control Module still, so I'll probably remove that tomorrow and order a new one unless everything works and the "no fault codes present" status flashes on a successful test of the ABS Test.

I may rebuild the fuel lines later anyway with the tools. The fuel filter is impossible to remove on my truck (too tight), so spinny spin line cutting on empty tanks and redoing the lines might be in my future on the rail.
 

Fellro

Moderator
Staff member
FYI, the factory lines are not stainless, just galvanized. They are a harder steel that the soft stuff from the parts stores.

Fuel filter is just held by the hose clamp, expand it enough to pass, take the conections loose and slip it out to the rear.
 

Kaajot

Micro Machine Manager
FYI, the factory lines are not stainless, just galvanized. They are a harder steel that the soft stuff from the parts stores.

Fuel filter is just held by the hose clamp, expand it enough to pass, take the conections loose and slip it out to the rear.

Yeah, so Keith came over a day earlier and although I have my tools for a future break-down, we were able to strip the coiling off the original *galvanized* line that broke and recreate a working double flair on a new end (cut off, filled down, flaired) for the fitting. So Brakes are working!

Updates on Brakes:

Massively had to brake bleed, faster with Keith over so that was good. Had a lot of crud come out at the back drums, but got the air out and put clear fluid in, full, no leaks.

Drove it. Drives like the back end is no longer a boat! Not at 35 not at 55. Also feels like four brakes are working, not just two. We tested the drums repeatedly while bleeding and you can hear good spring clicks functioning while under pressure and it appears to be funcitoning.

Bad news: ABS and Brake Control Short lights still come on. I'm gonna have to pull the ABS Module and replace it -- it makes the most sense still that this was the culprit to the ABS Light with no codes (literally would not go into Test Mode) and with a short that is shared with the Brake Control system.

Bonus, Keith saw the Neutral Safety Switch needed adjustment, I told him I was gonna do it later but he knocked it out in 2 minutes and no more jockeying the drives to start or get reverse lights on -- working solidly every time.

My mistake on the NSS Install -- just had it a little to far back/reared back. Keith said he just had a slight every so slight nudge downward/forward and it was good again to lock in place. I mean I knew, but I also knew how to work around it for now. Glad it's fixed though.
 

Kaajot

Micro Machine Manager
Got the RABS II Control Module out from behind glove box real easy.

Unfortunately, Rock Auto only has one Control Module in-stock and none of the 4 options match this part number. Is there an interchangeable part number that matches the following OEM ABS for a 1992 F150?

F2TF-2C018-AA is the module that I had.

I opened it up and couldn't find any blown capacitors or burns on the chipset. The only thing is a lot of green corrosion on the pins that plug into the wiring harness.
 

Fellro

Moderator
Staff member
The corrosion alone can cause the issue.
 

Kaajot

Micro Machine Manager
The corrosion alone can cause the issue.

Yup! Gonna clean the male pins on the module.

Question, any good method to cleaning the harness female pin receptacles? It's a very tight space, normally something to be desired but cleaning these out the best way is my goal to try to fix the shorting and hopefully fix ABS and Brake Control at same time.

I've got electrical spray cleaner, have dialectic grease for afterwards. Guessing a paperclip will be my best tool for the female end on the vehicle side?
 

Kaajot

Micro Machine Manager
Cleaned pins, haven't really got at the female side.

Pins really were green but it was the old grease covering them. Pins are shiny and silver, no evidence of corrosion. Plugging in today to see how it works. Check Engine and ABS Light went out once it was removed from the system.

We were also working on my engine, will add that to the older thread reagarding the S&J Engine Warranty. We did check the heat tab, not melted! Warranty is good. It had been painted blew, had to remove the paint with spirits to get to the silver tab and see a nice smooth shiny heat tab and solder intact.

Right now looks like it could be a combination of piston rings not seating/warped and maybe a blown manifold. There is blowback.

But during this diagnosis (have to do another series of test, he just did a leak down check on cylinder 1 and 4) we got talking about my splicing into the coil connector (repair) and how there's a third line. This goes to a radio condenser/capacitor. I've had blown feedback since a wire felt out when I was installing my amp and I've had feedback ever since, thinking I damaged the amp.

Turns out I may have blown this capacitor and didn't know any better. I've got two amps now, looks like the F700 will get a serious upgrade if this is the actual culprit.

I'm having a difficult time finding the Radio Capacitor/Condenser that could optionally tie into the Coil Plug wiring (it has a third wire that can go that way or through another wiring point). My truck is wired through the alternate wiring to the capacitor/condenser that eliminates radio feedback from the alternator whine/rpms.

I called NAPA, guy was unable to find it. Any ideas about a radio condenser/capacitor (also known as a distributor condenser/capacitor or alternator condenser/capacitor)?
 

Kaajot

Micro Machine Manager
Just mulling over the ABS Control Module I'm about to put back in. Trying to clean the female vehicle side and then apply dialectric grease and see how the truck performs.

Are there any ways to test the pins on the module to verify it's working as intended? I've given it a thorough inspection and the board and pins are good.

Worried if the module is good I'm likely looking at a true wire in the harness grounding out somewhere.

Note, I do have another short in the wiring system with the radio condenser capacitor. That might solve my short in my brake control, but I really hope that's not possible. But there is that.
 

Kaajot

Micro Machine Manager
Took the ABS for a drive.

Check Engine light remained off. ABS light turned on after I got over 35 mph, as usual.

It feels like the hydraulic unit is working mechanically better. Braking action IS there, but maybe slightly delayed.

Have not tried to pull the RABS II code, but believe I won't be able to trigger the fault flashes as my previous attempt before replacing the control unit and cleaning the contacts for the plug and adding new electrical grease.

So I've got two ways forward, unless there's a way to "bench test" the current ABS Control Module.

1. Shoot wires. Have no idea where I'd be shooting except I am pretty sure I can test the continuity from the test plug to the back of the wiring bundle (same color). That's the only wire I'll know its termination, but it shouldn't be the one causing an ABS Light fault with no codes (comm to PCM might be the wire to shoot?

2. Order another ABS Control Module off ebay, used, for $20-$40

2.1 Order a $125 new ABS Control Module off ebay. Unit I need is -AA ending. Believe its a 2, not a 3, starter digit.
 

Kaajot

Micro Machine Manager
Well, installed ABS Control Module, it still triggered an ABS Light after 35+ mph.

I attempted to pull codes through the RABS II fault test, shorted to negative/ground after turning on power (for approx 2 seconds, then remove short and should start flashing codes on ABS light). Nothing.

So my $20 diagnosis is there is a problem with a wire, but unsure where that short/wire is broken. Any ideas appreciated for the ABS light that won't go out.
 

Kaajot

Micro Machine Manager
And just like that, the ABS light stopped coming on, the brakes are now 100% working, no check-engine light, etc.

Compressed calipers to change wheel bearings and throw new aggressive wild country tires on front with new rims (got rid of factory for now) and put in new tie rods. Somehow this all made the difference.

Compressing calipers to clear an ABS fault hang-up? Doesn't seem likely, but I've got no other explanation.
 

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