Don't get your hopes up. Those connectors by the fuse panel are the CONSULT and OBD II connectors. The cruise control module is on the other side of the steering column, about in line with the center console. It's not all that bad, the connector sticks out sort of in the open, but then after having to replace the air mix door motor, nothing is that bad. If that motor goes out again, I'm tossing in a couple gallons of gas followed by a lit match! Anyhow, back on topic.

I want to throw out some miscellaneous info. I checked part numbers of the ASCD Control module and the 97 & 98 use the same one, # 18930-0L700. The other years are different. The vacuum pump is the same for all years of the 4th gen, # 18955-40U00.

pic of ASCD control module



photo of ASCD vacuum pump

 

Thanks Dennis. I should be able to get my hands on a multimeter this weekend and hopefully test things Monday.

 

All the ones I could check while not moving checked out fine at 14v. I gotta do the moving ones sometime. Maybe ill see if someone can ride with me and check while we are moving.

 

OK great, you're making progress. You have the needed conditions for the cruise to engage. So now the next part - is there a speed signal coming from the speedometer on pin 7 of the control unit and is the control unit sending power to the vacuum pump via pins 8 and grounding pin 9.

Before trying the drive and check voltages, you could go under the hood and put jumper wires on the vacuum pump and see if the motor runs. I think I'm going to go try this myself and see what I can see.

 

I see 4 wires on the plug going to the pump. Which ones would I try to jump? And would I go from the battery directly to the pump? If you know what wire to jump to let me know and I'll give it a shot now. Will I hear the pump do something?

 

Without looking at my car, you will have to go by wire colors. The pins you need to put jumper are diagonal from each other, not side by side. Unplug the connector from the pump so that you don't do any feedback to the control unit. 12 volts goes on the blue/white stripe wire and ground goes on the white/red stripe wire. Run a wire from the battery for the power and you can ground it anywhere.

Since I haven't done this, I can't say for sure if you will hear it. It is a small motor, so it probably won't be very loud. Maybe if you put your finger on the motor, you'll feel vibrations.

 

I just jumped the pump and it does come on. You can hear it run...it sounds like one of those car air pumps. It didn't do anything else, like move the cable, but it does run which I think is a good sign.

 

The motor running is a good sign. I expected that the throttle cable would not move. There are 2 air valves/solenoids in the vacuum pump assembly, one to let vacuum into the actuator, the other to let air in. You would have to ground one of the other pins to make the make the vacuum valve work while the motor is running.

I tried to do this on my 2000 but the vacuum pump assembly is a little less accessible and I couldn't get both jumper wires on at the same time. After a half hour of laying on top of the engine I was pi$$ed off enough to unplug the connector from the ASCD control module and do it from that end. Getting your hands on the control module is not as easy in the 5th gen as it is in the 4th. Nissan swapped locations of the BCM and ASCD modules so I had to pull out the radio and heater controls.

Then I decided that rather than jumper the motor, I would check voltages on the control module pins while driving. The results were basically like I expected but not entirely, a case of theory and reality are not always the same. I checked 5 pins on the control module, the VSS signal and the 4 wires going to the vacuum pump. So here is my experience checking those 5 pins. Sorry if it is wordy, I hope you can understand it.

These readings were taken with the connector plugged in to the control module and the car being driven and using cruise control.

All voltage readings are DC volts with the exception of the VSS speed signal.

Note that because the engine was running, the car's alternator is charging and the voltage will be above 12 volts. Not all alternators output the same exact voltage as mine (14.1 volts). Any measurements you get would be a little different as a result of this.


Pin 7 pink/blue stripe
VSS speed signal from the speedometer cluster.
This IS NOT a pure DC voltage. When the car was started and sitting still, the voltage read 4.7 volts DC. When driving, the DC voltage reading was jumping around wildly. Changing the meter to measure AC volts, the readings were steady.
Stopped - 0 volts AC
20 mph - 2.527 volts AC
30 mph = 2.583 volts AC
40 mph = 2.599 volts AC
50 mph = 2.604 volts AC
(I wonder if I goofed up writing down the numbers, the spread does not look right)

Pin 8 blue/white stripe wire
This pin supplies 12 volts to the vacuum pump assembly on pin 1. Internally this voltage is supplied to the MOTOR, the AIR VALVE and the RELEASE valve.
Car running and dash switch OFF - .1 volt.
Car running and dash switch ON - .7 volt.
SET button pressed and ASCD controlling speed - 14.1 volts.
Any time ASCD is not controlling the car's speed (i.e., you have stepped on the brake pedal to stop the car) this pin is .7 volt. When you press the RESUME button, this pin will go to 14.1 volts providing you are in the speed range for cruise to engage and operate.

Pin 9 white/red stripe wire
This pin activates the Vacuum Pump Motor (makes the motor run).
When the car was running but the ASCD was not engaged, this pin was .007 volts.
When the ASCD was set, the voltage reading went to around 12 volts but was not steady and jumped around. Changed the meter to AC volts but the reading was still jumping around. The ASCD control unit is evidently sending grounding pulses as needed, not on any regular basis. This means the motor is not running constantly or that it runs at variable speeds (or both). The closer the voltage to 12 volts means that the motor is running slower than full speed.

Pin 10 blue/yellow stripe wire
This pin makes the AIR VALVE solenoid work. I think (and I have nothing to back up this idea) that this solenoid controls the amount of vacuum that goes to the throttle actuator.
With the dash switch ON, this pin read .007 volt.
When the SET or RESUME buttons are pressed to engage the cruise control, this pin went to 7.7 volts.
When the car was accelerating to maintain the set speed, this reading was steady. But when the car had achieved the set speed and was on level ground, the voltage reading would vary. When going downhill, the voltage would decrease but was not steady.

Pin 14 blue/red stripe wire
This pin makes the RELEASE solenoid work to decrease the amount of vacuum in the throttle actuator, making the car slow down.
When the car was started, this pin read .001 volt.
When the dash switch was pressed, the voltage went to .007 volt.
When cruise control was engaged, this pin read 1.56 volts and varied .02 volt.
This voltage remained constant regardless of whether the ASCD was trying to speed up the car or slow it down. While the cruise control was engaged, I pulled on my parking brake to slow the car down. The ASCD tried to speed the car up and the voltage on pin 14 increased to 1.79 volts.

 

Dennis, Let me start off by saying, I really appreciate all your help! You have been great walking me thru all of this. I will have to do the drive test this weekend and see if I can do it by myself or if I need to grab a buddy to give me a hand.

It sure is going to suck if I test all the other wires and they all test out good. I don't know what direction we would head in next if that's the case. Anyway, I'll be in touch. With the holidays coming up, I am hoping I can get to it next Monday (my next day off). Thanks again Dennis...have a good Thanksgiving!

-Ryan

 

could be your clutch switch relay at the or another one of the relays for the system at the box near the power steering reservoir

 

Wouldn't there be some other symptoms if the clutch relay was shot? I'll throw a new one in there just to be sure but I'd think there would be other symptoms if it was shot.

 

likely so but it seems like a relay issue just because it all of a sudden stopped. The EL section will help out as mention

 

At this point in time I have to disagree with the relay theory. There is only one relay involved in cruise control for a manual trans, while the auto trans has two relays and also "borrows" the Theft Warning relay. The "clutch pedal" relay, called the "ASCD Hold" relay in the FSM, provides the power that goes through the brake pedal and clutch pedal switches.

One of the things I asked to be checked was pin 5 on the ASCD control module. Pin 5 is the power coming from the clutch pedal relay (aka ASCD Hold relay) and through the brake pedal and clutch pedal switches. Pin 5 had the power.

The relay is something that needs to be checked when you have a problem, it's just that it had all ready been checked before it was just now mentioned.

 

Dennis, If you're still subscribed to this, I have not completely abandoned this. I moved a few months ago and haven't really had the need for cruise, therefore, I have not done anything further with it. I have to take the car to the shop monday for an alignment...would they be able to hook a computer up to this and do the "driving" tests that I still have not checked yet?? If so, thats probably easier than me trying to drive with a multi-meter trying to get reading from the pins.

 

So I just sort of re-visited this today. I put the relay back in and got rid of the lazy mans mod. I wanted to see if the cruise light in the cluster would blink. So, I pushed the "set" button on the wheel and held it then pressed the "on" button on the dash behind the steering wheel. Well, the "cruise" light in the cluster started blinking but the cruise still would not engage. I'll dig some threads later to see what the flashing "cruise" means unless someone knows right off the top of their head.

 

I'm still interested in this problem, I'm no doubt going to learn something from this.

In general, a flashing cruise light means that 12 volts is missing from one of several pins on the control module. Which pin it is depends on what exactly is happening in the sequence of events, such as turning on the system initially, pressing the resume button, depressing then releasing the clutch pedal, whatever.

The FSM trouble shooting guide says that when the light flashes when pressing the switch on the dash, you should check the switches on the steering wheel. FSM pages EL-159 then jump to page EL-164. (read page EL-160 for extra credit, symptom # 2)

The FSM shows the procedure for using Consult to diagnose the cc, so that is evidently possible.

 

So, the stuff on EL-164 is the stuff that needs to be done when the car is in motion, right?

I snapped a pic of the clutch pedel switch for you to look at and make sure it's not missing anything. The clutch pedel DOES close the switch when the clutch is out and it DOES cancel the "cruise" light in the cluster when I step on the clutch so I think the switch is fine and not missing the piece that others say to check.

EDIT: I was just looking back on the things i have already tested with a multi-meter and it looks like i have already tested the brake and clutch pedal switches and they checked out with the proper voltage.

 

No driving needed for EL-164. You are checking the cruise control switches on the steering wheel to see if they are making and breaking the connection. In illustration A it is telling you to unplug the connector from the control module under the dash and check pins 1 and 2 for 12 volts with a certain button pressed. If the voltage measurements are incorrect, the illustration B says to check the continuity of the steering wheel switches on the switches. In both tests, the ignition switch is off.

 

Guess I missed it before but post #43 tells me I have already metered the switch pins.

 

You did, but only partially. When I compare my blurb (post 43) to the troubleshooting section in the FSM, I only told you to check for 12 volts on the pins, while the manual says to check for both 12 volts when the button is pressed and zero volts when the button is released. They want to make sure that a switch isn't shorted in the closed (button pressed) position.

And the FSM also asks you to check the CANCEL switch, which I ignored/overlooked.
Pin 1 is the RESUME switch, pin 2 is the SET switch.
The CANCEL switch puts 12 volts on both pins 1 and 2 at the same time.

I would like you to do the FSM test. I expect it will probably test good, but it isn't too hard to do and it is more thorough.

The photo of the clutch pedal switch looks good physically. You checked it electrically when you metered pin 5 (post 43).

 

I'll try to get around to more thoroughly checking the steering wheel switches this weekend. I also just looked at the brake Pedal switches and they look exactly like the clutch switch as far as the plunger thing goes. The plunger seems like it pushes fully in when the brakes are not applied. I looked at some other pics of peoples brake switches and theirs appear to have a larger rubber stopper on the end though. Doesn't seem like I need those since we tested those switches already and given that they get fully pushed in when I let off the brakes. Just thought it was odd that mine look like they do and others look different. Here's a pic of someone else's I found...you can see the difference as mine do not have that large rubber stopper



So for this, do I need to hook the (+) lead of the meter up to #1 and #2 at the same time?? Just run a jumper wire between the two of them?

 

Ok, I just did this test and did all 3 switches. They all metered at right around 12v when pressed and 0v when released. I was going to check the ohms on the pump but could not figure out if I needed to tap into the wire harness or test the prongs on the pump itself. I tried doing g the wire harness but was unable to get anything...tried with the key in the "on" position and with it off. The only time I got any ohm reading was when my finger touched the probe on the meter...does this info mean anything? I am pretty confident that the probe was touching the metal inside the plastic connector that connects to the pump. I tried testing ohms between pin 1 and 2, pin 1 and 3, then pin 1 and 4 as per the fsm.

 

Whenever you measure ohms, do not have the power on. If you did this on a circuit with a high current flow, you will damage the meter. In this case, I doubt that you hurt the meter.

You should be able to check the pump motor and the 2 solenoid valves through the unplugged ASCD control box connector. Pin 8 is common to the 3 things (connected to all of them) so one lead from your meter connects here and stays for the 3 measurements.

Pin 8 - common - blue/white stripe = pin 1 on the motor
Pin 9 - motor - white/red stripe = pin 4 on the motor
Pin 10 - air valve solenoid - blue/yellow stripe = pin 2 on the motor
Pin 14 - release valve solenoid - blue/ red stripe = pin 3 on the motor

Way back you did jumper 12 volts to the pump motor (pins 1 & 4) and it ran, so I have to think that for ohms testing, you were either not making connection with the contacts or you had the meter on too low of a scale. Give the wire harness thing a try.

 

OK, I'll give the wire harness a try.

I also asked the mechanic about it the other day and he printed me off this long trouble shooting thing from "Mitchell" something. Anyway, it had something in there about turn the key to "ON" and turn the main cruise switch on, then hold the brake for 5 seconds and if the light blinks xyz. In other words, it shows some different step by step trouble shooting procedures which I'm going to try. He was baffled too as to why the cruise does not work. I almost wonder if the actuator is shot and maybe just not creating the vacuum necessary to control the cruise system

 

you may need to get some electrical test clips and some pins to be able to be able to probe the wire harness connections for either the ohms or voltages. I posted a photo of mine in post 30. This would let you check the various pins while driving as you don't have to be holding on to the meter probes or anything. This is how I was able to get the voltages I wrote up in post 48.

As for the pump motor, that is going to be hard to tell if it is actually creating vacuum. You know the motor spins because you jumpered it with 12 volts. We don't know a) is the control module telling it to run; b) do the 2 vacuum valve solenoids have good resistance and c) are the vacuum solenoids being told to open and close.

Since you have the Mitchell Motor Repair test, it sure won't hurt anything to try it.

 

Well, I was going to try the harness test tonight...but i started with looking at my brakes cause they are only grabbing half the rotor in the rear. Ran into a big problem ...New thread on that issue with pics to come. FML