I also agree with checking for the ground straps breaking on the vehicle. There are sometimes straps that not only go from body to engine but body to frame rail under the truck - body to gas tank - axle in rear - all over. If they lose contact or break you can get weird loss of signal or weak signal in places. But blinkers going off can be from hazard as I said, or also trailer wires if you have trailer harness. Usually though flashing when key out would mean a flasher involved and that would just about always be hazard system. I posted the ABS test points above in post but you may just have to count the flashes. I have another page that tells you what the codes are if you need the info. Let us know what you get for a code. The usual ones I get are for erratic wheel speed or signal loss. According to the book it also turns on ABS if fluid low. Just a thought. You may have leaky line or pads wore down enough that fluid is lower.

 

I am sorry but most everybody on this 87-96 Forum knows that you, your book and machine are wrong.
Most books are wrong on our era of trucks, as we have to go by the each year Ford Shop Manual.
I can post you diagrams of Ford F53's & F & B-series Trucks through 1998 that have the OBD-1 system.
I just do not want some guy or gal new to the Forum reading your wrong information and costing them money.
I do not have to back up what I am saying as most on here know that I know what I am talking about.
What I have said above goes for both the F & B-series trucks and the F53, it seems that you know nothing about them.
So please do not putout bad information.
I think you need to get your money back on that machine as it dose not go along with any of the Ford Shop manuals through 1998.
I do not know anything about your Motorcycles to Audis or boats.
But it looks like your your machine does not test OBD-1 Ford trucks in the 80's and through 1998. I know a lot of them do not.

The page you posted is correct but does not say anything about using a code reader or scanner on the RABS. I did not say the RABS did not have a plug but you do not plug a scanner into it. You just count the flashes.
By the way most of the page you posted was just coped out of the FORD shop manual.

The 4 wheel ABS does use a special adapter and a special scanner for reading the codes as in the Ford vans but not in the trucks of this era.

As far as I am concern this case is closed!

 

You had better check to see if there is a wire (8 or 10 GA) from the NEG (-) post of the battery to the body of the truck (not the frame).
Also make sure the large cable goes from the NEG (-) post of the battery goes to the engine block and not the frame. The frame can be grounded too if you pull a trailer.

 

kind of off subject but the reason everything after 96 was "OBD 2" is because it was government mandated that all vehicles under 7999lbs and all non-diesel be equipt with the same style plug for service and mainly for state inspection purposes mainly regarding emmissions... the reason two trucks (a f-150 compared to a f-250,f-350, or diesel)of the same year (lets just say '98) one might have the OBD 2 connector and the other wont, is because emmissions are much different on heavy duty and diesel trucks and much more lax by the goverment... most high polution states just test their emmissions by checking if they blow lots of dark smoke and there-for will fail... if you would like to know more let me know as i work for NJ inspectio and i can post all the documents with this info and more...

 

1999 was the first year all Ford trucks were OBD-II.
For a example the 1998 F53 and the F&B trucks was still OBD-I in 1998.
The 1997 5.8L/7.5L (49 States Or Super Duty) was still OBD-I in 1997.