ASCD issues
01-02-2014, 06:46 PM
#1
ASCD issues
Trying to diagnose why my cruise control doesn't work in my 90 SE.
So far, following the FSM, I am to first, check for continuity between pin 3 on the ASCD harness (while plugged into the control module) and body. Check.
Turn on the dash switch, green light, good to go. Cruise light on instrument cluster is not illuminated (nor have I ever seen it lit) and therefore I assume this is to mean that it is only on when you actually successfully engage the cruise control via the steering wheel buttons (which had no effect)
Next step, I am to test the power circuit, checking for 12v between pins 3 and 4 with the key on and the dash switch on. Nothing.
No-go on this step means I need to test the power circuit harness, but it does not indicate where I ought to be checking. Wiring diagram indicates the battery connects to the ASCD module through the brake switch (diagram also appears to be indicating that it gets fed 12v via pin 11 I think)- which does appear to be working and yes, I have all the little rubber stoppers in place and appear to be in good shape! now that I think about it, I did not test either of the two brake switches for continuity/voltage.
Any suggestions?
Its worth noting previous owner apparently bypassed the starter relay by routing a wire directly from ignition switch to the starter via a relay and a connection to the positive terminal on the battery cables. Unknown as to WHY or whether this bypassed starter circuit would influence anything.
So far, following the FSM, I am to first, check for continuity between pin 3 on the ASCD harness (while plugged into the control module) and body. Check.
Turn on the dash switch, green light, good to go. Cruise light on instrument cluster is not illuminated (nor have I ever seen it lit) and therefore I assume this is to mean that it is only on when you actually successfully engage the cruise control via the steering wheel buttons (which had no effect)
Next step, I am to test the power circuit, checking for 12v between pins 3 and 4 with the key on and the dash switch on. Nothing.
No-go on this step means I need to test the power circuit harness, but it does not indicate where I ought to be checking. Wiring diagram indicates the battery connects to the ASCD module through the brake switch (diagram also appears to be indicating that it gets fed 12v via pin 11 I think)- which does appear to be working and yes, I have all the little rubber stoppers in place and appear to be in good shape! now that I think about it, I did not test either of the two brake switches for continuity/voltage.
Any suggestions?
Its worth noting previous owner apparently bypassed the starter relay by routing a wire directly from ignition switch to the starter via a relay and a connection to the positive terminal on the battery cables. Unknown as to WHY or whether this bypassed starter circuit would influence anything.
Last edited by Levsimus; 01-02-2014 at 06:48 PM.
01-03-2014, 02:33 PM
#2
Do your brake lights work? if so then the brake light switch is not at fault.
The micro switch to the left of the brake light switch is what you need to check.
If this micro switch is faulty your cruise control will not engage pending that there are no other issues with the cruise control system such as the actuator on the passenger fender well in front of the strut tower, bad solder joints in the cruise control amplifier(computer)or a bad switch on the steering wheel, corroded connector pins just to give you an idea.
There's no telling what the PO did under the dash while bypassing the starter relay but that shouldn't have anything to do with the functionality of the cruise control.
The micro switch to the left of the brake light switch is what you need to check.
If this micro switch is faulty your cruise control will not engage pending that there are no other issues with the cruise control system such as the actuator on the passenger fender well in front of the strut tower, bad solder joints in the cruise control amplifier(computer)or a bad switch on the steering wheel, corroded connector pins just to give you an idea.
There's no telling what the PO did under the dash while bypassing the starter relay but that shouldn't have anything to do with the functionality of the cruise control.
01-03-2014, 04:14 PM
#3
Member
Join Date: Feb 2010
Location: DFW- Texas
Posts: 115
If the FSM says it's a bad controller, here's a cheap one:
http://www.ebay.com/itm/ASCD-CONTROLLER-MODULE-NISSAN-MAXIMA-1988-1989-1990-1991-AT-18930-85E11-OEM-/190825986690?pt=Motors_Car_Truck_Parts_Accessories&hash=item2c6e1d7a82&vxp=mtr
I had a 90 GXE where the OEM ASCD went out. I put in a salvage yard controller and it worked for about a week and then went dead for good. If all your connections, switches and servo unit are good, then it's the controller that's bad.
http://www.ebay.com/itm/ASCD-CONTROLLER-MODULE-NISSAN-MAXIMA-1988-1989-1990-1991-AT-18930-85E11-OEM-/190825986690?pt=Motors_Car_Truck_Parts_Accessories&hash=item2c6e1d7a82&vxp=mtr
I had a 90 GXE where the OEM ASCD went out. I put in a salvage yard controller and it worked for about a week and then went dead for good. If all your connections, switches and servo unit are good, then it's the controller that's bad.
01-03-2014, 08:16 PM
#4
Thanks for the link, puck. Hopefully it doesn't come to replacing it - but first, another problem.
I realized that testing for 12v between 3 and 4 wasn't going to yield any results if I didn't check upstream in the circuit first. Pin 11 is indeed the stop light switch and battery circuit and would yield 12v as long as the switch was functional, as Grumpy confirmed. Basically, I realized I was going about this all wrong, looking at the diagram all wrong, I mean. The diagram indicates a connection to the ignition, looking for either "on" or "start" to a fuse, then down to the ASCD hold relay, and in combination with that, the dash switch.
So with this in mind, I pulled the hold relay and applied 12v to the circuit. Click. Good relay. Car was off, turned key to "On" and jumped the female ends of the relay plug in the fusebox. The hot circuit side, I mean. Hooked up the multimeter to auto range for volts between the open/close circuit controlled by the relay. Press switch, it doesn't stay on, realize that I need to hold the switch ON as there is no relay to maintain the circuit. Switch on yielded very little voltage, maybe .20 volts.
Damn. turn car on, test again, same thing. Oh well, put everything back together, go back inside. Realize I left my phone and wallet in my toolbox at work, good time to test and see if anything changed. Except now the ASCD switch does NOTHING. Not even light up. On my way back home I tried to turn on the heater and it didn't come on. None of the buttons (manual climate control) worked, the Off-4 settings did nothing, hot, cold, defrost, nothing worked. No blower, the buttons don't even light up.
What the hell did I break now? Defrost switch also does not light up when pressed either, however all dash illumination appears to be functional.
FML.... dug through the wiring diagrams, I can't even see how these two systems are even linked and I can't figure out which fuses and relays control the system.
I realized that testing for 12v between 3 and 4 wasn't going to yield any results if I didn't check upstream in the circuit first. Pin 11 is indeed the stop light switch and battery circuit and would yield 12v as long as the switch was functional, as Grumpy confirmed. Basically, I realized I was going about this all wrong, looking at the diagram all wrong, I mean. The diagram indicates a connection to the ignition, looking for either "on" or "start" to a fuse, then down to the ASCD hold relay, and in combination with that, the dash switch.
So with this in mind, I pulled the hold relay and applied 12v to the circuit. Click. Good relay. Car was off, turned key to "On" and jumped the female ends of the relay plug in the fusebox. The hot circuit side, I mean. Hooked up the multimeter to auto range for volts between the open/close circuit controlled by the relay. Press switch, it doesn't stay on, realize that I need to hold the switch ON as there is no relay to maintain the circuit. Switch on yielded very little voltage, maybe .20 volts.
Damn. turn car on, test again, same thing. Oh well, put everything back together, go back inside. Realize I left my phone and wallet in my toolbox at work, good time to test and see if anything changed. Except now the ASCD switch does NOTHING. Not even light up. On my way back home I tried to turn on the heater and it didn't come on. None of the buttons (manual climate control) worked, the Off-4 settings did nothing, hot, cold, defrost, nothing worked. No blower, the buttons don't even light up.
What the hell did I break now? Defrost switch also does not light up when pressed either, however all dash illumination appears to be functional.
FML.... dug through the wiring diagrams, I can't even see how these two systems are even linked and I can't figure out which fuses and relays control the system.
Last edited by Levsimus; 01-03-2014 at 08:21 PM.
01-04-2014, 09:53 AM
#5
Member
Join Date: Feb 2010
Location: DFW- Texas
Posts: 115
If you only got .20 volts on that relay reading, the circuit is probably open and not functioning.
All I can think of re: the climate control not working etc. is you blew a fuse or a relay is stuck open or closed. I don't think you burned up a connector or wire. After checking all the obvious things, disconnect the battery and let the computer reset (you know, the old Windows routine!)
I also think both stop light switch and cancel switch on the brake pedal have to work properly or you won't pass the cut-off circuit check.
I'm not good at electrical diagnostics when it comes to circuit diagram analysis. But I don't think you broke something or burned up a conductor, etc. When I was working on my 90's cruise control, I just followed Trouble Diagnosis 1-5, but I never could get past 1, so I knew it was a bad controller.
All I can think of re: the climate control not working etc. is you blew a fuse or a relay is stuck open or closed. I don't think you burned up a connector or wire. After checking all the obvious things, disconnect the battery and let the computer reset (you know, the old Windows routine!)
I also think both stop light switch and cancel switch on the brake pedal have to work properly or you won't pass the cut-off circuit check.
I'm not good at electrical diagnostics when it comes to circuit diagram analysis. But I don't think you broke something or burned up a conductor, etc. When I was working on my 90's cruise control, I just followed Trouble Diagnosis 1-5, but I never could get past 1, so I knew it was a bad controller.
01-04-2014, 11:46 AM
#6
If you only got .20 volts on that relay reading, the circuit is probably open and not functioning.
All I can think of re: the climate control not working etc. is you blew a fuse or a relay is stuck open or closed. I don't think you burned up a connector or wire. After checking all the obvious things, disconnect the battery and let the computer reset (you know, the old Windows routine!)
I also think both stop light switch and cancel switch on the brake pedal have to work properly or you won't pass the cut-off circuit check.
I'm not good at electrical diagnostics when it comes to circuit diagram analysis. But I don't think you broke something or burned up a conductor, etc. When I was working on my 90's cruise control, I just followed Trouble Diagnosis 1-5, but I never could get past 1, so I knew it was a bad controller.
All I can think of re: the climate control not working etc. is you blew a fuse or a relay is stuck open or closed. I don't think you burned up a connector or wire. After checking all the obvious things, disconnect the battery and let the computer reset (you know, the old Windows routine!)
I also think both stop light switch and cancel switch on the brake pedal have to work properly or you won't pass the cut-off circuit check.
I'm not good at electrical diagnostics when it comes to circuit diagram analysis. But I don't think you broke something or burned up a conductor, etc. When I was working on my 90's cruise control, I just followed Trouble Diagnosis 1-5, but I never could get past 1, so I knew it was a bad controller.
And of course, figure out why none of my switches work and the MCC suddenly **** the bed and killed what little heat I did have coming out of that clogged core. I might've killed the switch or something. I know that when I was driving around with the dash apart for a while, I had that switch panel disconnected with only the foglight and cruise control switches attached, and the cruise control switch did NOT work. Foglights did but that being because it is an on-off switch rather than a rocker type switch like the CC. Once I put the dash back together, the cruise control switch started working (well, the light on the button did, anyways).
So I guess I could've blown an accessory fuse since I think they're on the same fuse but I can't figure out which ones are which, the relays aren't clearly indicated as climate control/heater, just one for AC and both heater/blower fuses are good. It was dark at the point I realized all this stuff was out of whack though, so today in the relatively warm shop may be a better option... I just kinda didn't want to go back to the shop on my day off!
01-04-2014, 12:48 PM
#7
Member
Join Date: Feb 2010
Location: DFW- Texas
Posts: 115
If I'm following you right, you haven't checked all your fuses? Need to do that first. But I'm not sure why you would've blown the climate control fuse unless you shorted that circuit.
You need to get power to the ASCD controller before you can test anything else. Once you verify power to the controller, the next steps require that input signals such as brake sw, speed sensor and set switch are being processed within the controller. I think when you push the Set switch, you should hear a faint little click inside the controller. If not, then the controller is bad. Remember, the controller processes all these signals and its output is voltage to the servo that increases or decreases throttle pull. So there's probably a little Eprom chip or diode in there that goes bad. I went through all this w/ my old 90 and gave up because I didn't want risk buying more used controllers and too cheap to belly up for a new Nissan controller. then I bought a 2006 Maxima and sold this one.
You need to get power to the ASCD controller before you can test anything else. Once you verify power to the controller, the next steps require that input signals such as brake sw, speed sensor and set switch are being processed within the controller. I think when you push the Set switch, you should hear a faint little click inside the controller. If not, then the controller is bad. Remember, the controller processes all these signals and its output is voltage to the servo that increases or decreases throttle pull. So there's probably a little Eprom chip or diode in there that goes bad. I went through all this w/ my old 90 and gave up because I didn't want risk buying more used controllers and too cheap to belly up for a new Nissan controller. then I bought a 2006 Maxima and sold this one.
01-04-2014, 05:21 PM
#8
If I'm following you right, you haven't checked all your fuses? Need to do that first. But I'm not sure why you would've blown the climate control fuse unless you shorted that circuit.
You need to get power to the ASCD controller before you can test anything else. Once you verify power to the controller, the next steps require that input signals such as brake sw, speed sensor and set switch are being processed within the controller. I think when you push the Set switch, you should hear a faint little click inside the controller. If not, then the controller is bad. Remember, the controller processes all these signals and its output is voltage to the servo that increases or decreases throttle pull. So there's probably a little Eprom chip or diode in there that goes bad. I went through all this w/ my old 90 and gave up because I didn't want risk buying more used controllers and too cheap to belly up for a new Nissan controller. then I bought a 2006 Maxima and sold this one.
You need to get power to the ASCD controller before you can test anything else. Once you verify power to the controller, the next steps require that input signals such as brake sw, speed sensor and set switch are being processed within the controller. I think when you push the Set switch, you should hear a faint little click inside the controller. If not, then the controller is bad. Remember, the controller processes all these signals and its output is voltage to the servo that increases or decreases throttle pull. So there's probably a little Eprom chip or diode in there that goes bad. I went through all this w/ my old 90 and gave up because I didn't want risk buying more used controllers and too cheap to belly up for a new Nissan controller. then I bought a 2006 Maxima and sold this one.
Believe me, I'd sell this thing and go newer if I could but unfortunately my situation is such that its not really possible right now. Even if I did sell it I'd probably just end up with another 3rd gen
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