My ABS light came on and the Scan Tool (Blue Driver- I like this one, it is small, saves reports to my iphone and is very easy to use) gives me a code of “C1185 - ABS Power Relay Output Circuit Failure” and says to replace the “ABS Control Module”. This is on a 2003 F150 Crew Cab 2-WD with 4.6L and 213500 miles. Engine is clean (no oil leaks), runs good.
My question is this, the replacement (remanufactured) says to replace the fluid in the system; if I replace the master cylinder and the Vacuum Power Brake Booster (the truck has recently started making a “bellows noise”, usually when I stop and park, but can occasionally be heard at any time) can I replace the brake fluid with DOT 5 (Silicone Fluid - Genuine Ford PM-21 DOT 5.1) without replacing anything else so long as I drain all the fluid out and then use the Phoenix (2003-B V-12 Reverse Brake Bleeder and bleed all the lines (longest first) up to the engine compartment with the Master Cylinder not connected first?
Is this a good plan, or is there something I am missing?
Hopefully I will get a response within 24-48 hours…. Thanks.
DOT 5.1 brake fluid is glycol based, not silicone, and is compatible with DOT 3 and 4 fluids. The main difference is a higher boiling point. So you don't need to do anything special to switch to DOT 5.1, just directly flush out the brake system with it.
On the other hand DOT 5 is silicone based and is not compatible. You'd need to thoroughly flush out the entire brake system with denatured alcohol before switching to DOT 5 fluid. Some say new rubber seals should be installed as well.
Silicone DOT 5 fluid is not hygroscopic, does not absorb moisture. Although this sounds like a good thing it means that any moisture entering the brake system will drop to the lowest point instead of being dispersed and will cause the calipers or wheel cylinders to corrode internally. DOT 5 fluid is mainly used in collector cars that see little use.
Wow, thank you for the very informative information. I’ve used DOT5 on new cars and had the dealership replace the fluid; worked great - I live in Olympia and the DOT 5 has greatly reduced corrosion of the caliper cylinders. I used to have lots of problems requiring replacement of calipers, with the DOT5 used I’ve not had to replace a caliper for rust in the cylinders since.
So, should I replace all 4 Calipers after flushing the system, or just replace all of the O-Rings in the Caliper Cylinders (if the Calipers Pistons & Cylinders are OK)?
It's not something I've done myself so I cannot say from personal experience, I'm just cognizant of the differences between DOT 5 and 5.1. There should be plenty of information online for converting to DOT 5 silicone from conventional glycol-based fluids.
I’ve used DOT5 on new cars
it might have been DOT 5.1 which, again, is something completely different
