stufrus Posted June 21, 2014 Share Posted June 21, 2014 Having problems with my cruise control. It does not work many more. I'd like to check the vacuum diaphram module - that thing that has a vacuum line connected to it, and has a cable running to the accelerator. If I pull the vacuum line off of the back of this unit, and rev the engine, placing my finger over the hose nipple - should I feel vacuum? Does the truck have to be running in gear? Is there a certain rpm that I must achieve to feel sufficient vacuum to operate the ASCD unit? how much vacuum should I feel? I do not think that any switches need to be engaged - as the diaphram module is connected directly to the accelerate with no electronics. Any suggestions?? Link to comment Share on other sites More sharing options...
ahardb0dy Posted June 21, 2014 Share Posted June 21, 2014 (edited) There is a small vacuum pump next to the that diaphragm, if the cruise is not being told to turn on the pump will not produce vacuum and you will not feel it on the hose, it shouldn't have vacuum on that hose unless all the conditions are met for the cruise to work, ex. driving above 40 mph, see this thread for more info on the cruise not working: http://www.nissanpathfinders.net/forum/topic/38266-94-se-4x4-pathfinder-cruise-control-help/ Edited June 21, 2014 by ahardb0dy Link to comment Share on other sites More sharing options...
stufrus Posted June 21, 2014 Author Share Posted June 21, 2014 Thank you. Been playing with the ASCD module all morning. Using the FSM that I downloaded from your site, I opened up the inside cargo panel to expose the ASCD control unit. And, took several readings with the volt meter before I got a bad reading. The FSM said to then check the switches under the break pedal. found one error in the FSM when it referred to pg 67 for the testing procedures for the brake and ASCD switch, so when I was reading the testing procedures for testing these switches, it refered to the male end of the plug, when it fact - this was a second error in the FSM pg 73 ( I beleive) where it should have refered to the female end or the switch body itself. The brake switch checked fine and according to the continuity described in the FSM (, however, the ASCD switch had no continuity with or without the pedal depressed. It was a bad switch! Put a jumper in the harness (male) side of the switch, and retook the voltage reading that failed earlier. Read 12v as it should have the first time. I'll replace the ASCD switch - and then carry on with things if the cruise continues not to work. The FSM offers a systems check for the pump - but, I'd need to feed 12v to the pump, and I got tired of playing for the day. Link to comment Share on other sites More sharing options...
adamzan Posted June 22, 2014 Share Posted June 22, 2014 I had that switch fail too. You can still use the cruise without it, as the brake light switch is a failsafe and deactivates the cruse control as well. I honestly never got around to changing it on my old pathy. Link to comment Share on other sites More sharing options...
ahardb0dy Posted June 22, 2014 Share Posted June 22, 2014 Was going to say try the cruise with the jumper wire in place of the switch you think is bad and see if it works Link to comment Share on other sites More sharing options...
stufrus Posted June 22, 2014 Author Share Posted June 22, 2014 ahardb0dy - thought about doing that, thinking that the jumper on the ascd plug might close the ascd circuit for the cruise control to work. And, I still might do it, just to eliminate other possible faults, like the pump, or ascd control module. I've tried to activate cc with the jumper, but - the truck was static and not moving. Understand that it must be traveling some 40mph to activate the cc. So, perhaps today I can put it on the road and test the system with the jumper in place. Let you know what happens. Already ordered my ascd switch. Thanks Link to comment Share on other sites More sharing options...
ahardb0dy Posted June 22, 2014 Share Posted June 22, 2014 Welcome, when my cruise wasn't working in the 94 I had it was the vacuum hose to the actuator, than the steering wheel contacts started acting up but i fixed that Link to comment Share on other sites More sharing options...
stufrus Posted June 23, 2014 Author Share Posted June 23, 2014 ahardb0dy - This is a confirmation that, by jumping the harness terminals on the ascd switch, that cruise control will operate normally, and that the brake switch, when working properly and alone from the ascd switch, will cancel cruise control. took my 94 pathfinder for a test run yesterday. It has been years since the cruise control worked. I repaired a vacuum leak, checked continuity at the steering wheel switch, and followed the FSM to trouble shoot and meter the voltage at various points at the ASCD control Module. When I failed to find a recommended voltage at the ASCD control unit, the guide lead me to the brake and ascd switches. Though, the FSM referred me to the "male" or harness side of the switch, the FSM was asking to check for continuity. It took me a little while to understand that this was a FSM troubleshooting error, and that what the FSM should have shown on the guide was an image of a "female" plug, namely the switch itself, as continuity in the harness would be almost impossible unless these wires went nowhere and ended nowhere. As it was - the break switch tested accord to the continuity table in the FSM, but the ascd switch did not. The ascd switch showed an open with or without the pedal depressed. It was bad. When I jumped the ascd switch harness , and took my voltage reading at the ascd control module, the recommended voltage was present. With the jumper in place, and the harness dangling, I took the truck for a spin. Reached 40mph and activated my cruise control main switch then set my speed switch. Tried this several times - and played with the cancel, accelerate, switches, was able to cancel cc by tapping the brake pedal - everything worked. A new ascd switch is in route, and when received, I'll install it as I feel it should be there. But - the suggestions that the cruise control system will operate normally without this ascd switch - are in fact TRUE. Until again, after I install the new ascd switch. Link to comment Share on other sites More sharing options...
ahardb0dy Posted June 23, 2014 Share Posted June 23, 2014 Glad you figured it out. Link to comment Share on other sites More sharing options...
ThaBigPerm Posted June 23, 2014 Share Posted June 23, 2014 Mine's been on the blink since I got it last year. CC light comes on with the master switch, but no workie. No apparent vaccuum leaks. Now I'll test the pedal switch continuity. I did have the crumbly switch "buttons" that ran the battery down (by leaving the brake lights on 24-7) and that I suspected was also the cause of the CC issue, but that didn't fix it. Thanks for the writeup. Link to comment Share on other sites More sharing options...
adamzan Posted June 23, 2014 Share Posted June 23, 2014 Just for the record, the cruise does NOT run off the engine vacuum, regardless of what anyone tells you. It has it's own little vacuum pump. The most common things to stop the cruise on these trucks seems to be the steering wheel contacts (94-95) and the brake pedal switches. Link to comment Share on other sites More sharing options...
Mr_Reverse Posted July 9, 2014 Share Posted July 9, 2014 I had mine quit working in my 93, that took almost 9 months to figure out. The cruse would work fine until I turned on the lights. Then it would quit. I spent a lot of time chasing wires and switches looking for the problem and never found it until I was out in the middle of nowhere one night and got out of my truck and walked behind it. I noticed that with the parking lights on, the high mount brake light was glowing dimly and my right taillight was a little brighter than the left. Turned out to be a problem in the bulb, the parking light filament holder was barely touching the brake light filament holder. Replaced the bulb and it all worked correctly again. Just when you think you have seen it all, there is always another surprise... Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now