Help Needed down under

[kiwi f150]

Hi Guys i'm hoping one of you can help me with this problem.

Ocasionally when the truck is warm the rabs light and the brake warning light come on on the dash - when this happens the brake pedal "firms" up and there is a noise from under the bonnet similar to but somewhat louder than the standard ford pwr steering pump whine - iv'e also noticed that the fuel economy drops off when this condition is occuring as well.
I've read the codes and all seems to be fine but am unfortunately too deaf to be able to pinpoint the noise to anywhere specific.
Turning the engine off and resarting it makes the lights go out and the brake pedal return to normal operation.

I've added a pic but its not too good a quality being from a cellphone.

Cheers Mark

 

[Truckin4life]

When it firms up, is it comparable to how firm the peddle is when the truck is off?

Or is it not quite that firm...

I do believe the Master cylinder is Vac, so maybe you have a vac leak or something?

 

[Truckin4life]

I am merely thinking out loud here, i dont have any idea whats really going on... Sorry i cant be of more help.

 

[kiwi f150]

When it firms up, is it comparable to how firm the peddle is when the truck is off?

Or is it not quite that firm...

I do believe the Master cylinder is Vac, so maybe you have a vac leak or something?

Yep its frim just like the engine was off - il check to see if it leaks down in vacuum - although if it is a crook booster it shouldn't be intermittent should it.

 

[Fellro]

Sounds like for whatever the reason that the ABS is actually doing it's job, so if it is happening in loose traction conditions, that would be normal. If the light comes on at the same time of the noise, it is the ABS unit working. The question would be if this is happening randomly, or when you have traction issues.

 

[Alvin in AZ]

x2 on everything but.

I'm not having any ABS lights coming on in my '91 Bronco or having it act
funny in anyway and I stop-on-dirt and I stop with one-side-dirt and one
side-pavement and crazy stuff like that all the time.

I think something is wrong with his ABS and it may be something important
or not important at all. What I read way back was the way to disconnect
the newer systems was to remove the power wire to the system. Can you
guys tell 'im how to do that and he can see if it makes any changes at all?

{edit}
My Ex's brand new '93 S10 Blazer's 4-wheel ABS sucked donkey dick!
I hated that system with a passion.
It wouldn't stop when I wanted it to.
I never did disconnect it but was fixin' to.
She packed her #$% and left just before I got to that. LOL

Alvin in AZ
ps- "only a jackass would like it"
pps- I live on a dirt road the postal-people won't drive up.

 

[kiwi f150]

Sounds like for whatever the reason that the ABS is actually doing it's job, so if it is happening in loose traction conditions, that would be normal. If the light comes on at the same time of the noise, it is the ABS unit working. The question would be if this is happening randomly, or when you have traction issues.

Hi Roger - Its just a random thing - the old girl doesn't have traction issues
unless its on wet grass or dirt roads .

With the ABS in my more modern cars when you get in a situation where its working the brake pedal will shudder under your foot - in the truck all that is happening is that both the ABS and brake warning lights come on at the same time as the noise and the brake pedal needs a firmer push to activate.

Cheers Mark

 

[kiwi f150]

x2 on everything but.

I'm not having any ABS lights coming on in my '91 Bronco or having it act
funny in anyway and I stop-on-dirt and I stop with one-side-dirt and one
side-pavement and crazy stuff like that all the time.

I think something is wrong with his ABS and it may be something important
or not important at all. What I read way back was the way to disconnect
the newer systems was to remove the power wire to the system. Can you
guys tell 'im how to do that and he can see if it makes any changes at all?

{edit}
My Ex's brand new '93 S10 Blazer's 4-wheel ABS sucked donkey dick!
I hated that system with a passion.
It wouldn't stop when I wanted it to.
I never did disconnect it but was fixin' to.
She packed her #$% and left just before I got to that. LOL

Alvin in AZ
ps- "only a jackass would like it"
pps- I live on a dirt road the postal-people won't drive up.

Hi Alvin - I picked up a Haynes manual for the truck a while ago so i'll have a dig through that and disconnect the abs system and see what happens - it just happens randomly though and normally when the truck is on longer trips.

Cheers Mark

 

[fatherdoug]

Could you temporarily disconnect the ABS sensor on the differential?

 

[Fellro]

my 88 does it once in a while, then it goes back off, but the brakes never change. What year exactly are we dealing with? 91 and older, you can unplug the sensor at the rear and be ok, 92 up, that is also the speed sensor. (If you ever have to go to the parts store for a VSS on the 92 up, be prepared to find it as the ABS sensor, our system has it listed that way, the listing they have for VSS goes in the tranny, and there is no such thing on a 92 and newer.)

 

[kiwi f150]

my 88 does it once in a while, then it goes back off, but the brakes never change. What year exactly are we dealing with? 91 and older, you can unplug the sensor at the rear and be ok, 92 up, that is also the speed sensor. (If you ever have to go to the parts store for a VSS on the 92 up, be prepared to find it as the ABS sensor, our system has it listed that way, the listing they have for VSS goes in the tranny, and there is no such thing on a 92 and newer.)

Hi Roger - mine is a 87 so tomorrow i will unplug the sensor and give it a few days to see if it comes on again - parts for this truck are a real pain out here as the main stores (repco ,bnt ,supercheap) don't have any listings and independent parts shops are just about a thing of the past now - Ford sold the F150 over in Australia for many years but i'm finding it cheaper to get parts sent out from Northern Auto or Rockauto - if your company does mail order to New Zealand i would rather deal with you as i'd prefer to give my money to someone i know than some faceless order form.

Cheers Mark

 

[Fellro]

It would be Autozone... but if needed, I can do it for you as well. Then we can validate what is being sent is the part that we want to be sent... Shipping from vendors is free to customers at the store, so the only shipping would be from me to you.

Don't be too surprised if the light comes on all the time with the sensor unplugged, but it shouldn't activate the ABS either. You can then determine if it is the abs, or something else going on. Sometimes the sensor gets metallic filings stuck to it, so it can be taken out and cleaned off and fix the issue as well. At least when it is doubled as a speed sensor that happens, when the speedo goes nuts on the later trucks.