Cruise Control self test.

[davebb]

97 Explorer 5.0L and a 4R70W in a 68 Bronco. Cruise control self test shows 2 flashes. Meaning brake switches signal. Both switches and their circuits test good. Do you think this is a bad cruise control servo? Don't know what else to look into.

 

[tinman_72]

I cannot offer any help but it sounds like a cool build. Do you have a build thread?

 

[davebb]

I cannot offer any help but it sounds like a cool build. Do you have a build thread?

I didn't think to do that. I do have some random pics though. I'd have to transfer them to my pc first though.

 

[J_C]

97 Explorer 5.0L and a 4R70W in a 68 Bronco. Cruise control self test shows 2 flashes. Meaning brake switches signal. Both switches and their circuits test good. Do you think this is a bad cruise control servo? Don't know what else to look into.

Can you elaborate on "both switches and their circuits test good"? Just wondering how exhaustive the test was, if all the way to the CC module, and that the switches return to open circuit when the pedal is released (not just the switches tested in isolation)?

They are both just giving the CC module 12V, are you doing the self test with the brake pedal not pushed? If so, I would try unplugging the brake pedal switch(es), one at a time, to see if the error goes away, in case the switch is intermittently engaging aka worn out, or the pedal is sticking or weak master cylinder return spring... if that's the only spring return for the pedal on the Bronco.

 

[davebb]

Can you elaborate on "both switches and their circuits test good"? Just wondering how exhaustive the test was, if all the way to the CC module, and that the switches return to open circuit when the pedal is released (not just the switches tested in isolation)?

They are both just giving the CC module 12V, are you doing the self test with the brake pedal not pushed? If so, I would try unplugging the brake pedal switch(es), one at a time, to see if the error goes away, in case the switch is intermittently engaging aka worn out, or the pedal is sticking or weak master cylinder return spring... if that's the only spring return for the pedal on the Bronco.

Hi and Thanks. Both switches, the one on the brake pedal and the one on the master cylinder. I've done the self test by the book a whole bunch of times and checked each circuit forwards and backwards. The only thing that came up is that the brake pedal feed to the cc module has aprox 7.5V with the key on and that's coming from the PCM. My guess is that 7.5V must be a reference voltage that the cc self test uses, otherwise how would the self test know there's a problem with that circuit, it only gets voltage when the pedal is pushed and the test is with the pedal not pushed.
I ordered a used cc servo from Ebay. I guess we'll see how that changes things.

 

[davebb]

I ordered a used cc servo from Ebay. I guess we'll see how that changes things.

Update. Well the first one I got from Ebay was used and wouldn't even go into the self test. Got a refund on that one. Then ordered a NOS one brand new. It does the same thing my old one does. So I thought about the 7.5 volts coming from the PCM and removed that brake circuit wire from the PCM plug and that made the self test in the cc pass. Can't test drive it right now though because the front seal in the fresh 4R70W trans blew out. I started another thread asking why the PCM needs the brake input.
Thanks all!