cruise control trouble (2 Viewers)

[FranceJohnson]

These sensors are well out of my wheelhouse, so if some EEs would like to chime in that would be helpful. I was bouncing some ideas off my father-in-laws head, he is an EE. So as far as the resistor, he said the resistor would go from the signal wire (to the CC module) to the ground on the sensor; this would be used to drop the voltage of signal. However, he stated that in his experience, most modules will do this internally. I am inclined to agree with this, but this could be confirmed by someone taking the voltage from the VSS from the (harness) Pin-3; I would but I have already destroyed my VSS. Remember to supply the +12V to (harness) Pin-1...

Here is where I am a little foggy on Hall Effect sensors themselves. I have read that the HE sensor needs to have the proper pole facing the toward the ring magnet. My ignorance is this, if the HE sensor is Omnipolar, will that affect it if the pole is not correct, at least as far as the CC module is concerned?

 

[FranceJohnson]

I found this on Allegro MicroSystems website about Omnipolar Hall Effect Sensors:

"Q: How do I orient the magnets?

A: The magnet poles are oriented towards the branded face of the device. The branded face is where you will find the identification markings of the device, such as partial part number or date code.

Q: Can I approach the device back side with the magnet?

A: Yes, however bear this in mind: if the poles of the magnet remain oriented in the same direction, then the orientation of the flux field through the device remains unchanged from the front-side approach (for example, if the south pole was nearer the device in the front-side approach, then the north pole would be nearer the device in the back-side approach). The north pole would then generate a positive field relative to the Hall element, while the south pole would generate a negative field.

Q: Are there trade-offs to approaching the device back side?

A: Yes. A "cleaner" signal is available when approaching from the package front side, because the Hall element is located closer to the front side (the package branded face) than to the back side. For example, for the "UA" package, the chip with the Hall element is 0.50 mm inside the branded face of the package, and so approximately 1.02 mm from the back-side face. (The distance from the branded face to the Hall element is referred to as the "active area depth.")"

Seems like the best signal would come from facing the "branded" side of the HE down towards the ring magnets underneath. This page also confirms the function and wiring of the resistor, but does not confirm its necessity for this with the CC Module. That will require the test to see what the stock VSS output signal is.

 

[FranceJohnson]

My first attempt at correcting this did not work, although it might have been due to not using the Texas Instrument sensor. I have purchased the correct sensors and will do this again. I intend to start a new thread with will detail the CC diagnostics, and VSS rebuild and testing procedures of a 91/92. Once I have completed the job and have a known working sensor, I will post the link to it from here.

 

[FranceJohnson]

I could use some additional help diagnosing my issue. I have completed the TI Hall Effect sensor install, I checked to make sure I had good continuity from the pin to the sensor, and no touching wires after installing. My issue is after installing and doing the CC diagnostics test, I fail the speed sensor portion.

When stopped the CRUISE light is OFF. As soon as I start moving it is illuminated (never blinks), even as I drove up to 55mph. CRUISE light turns off as soon as I hit the brakes.

So here is where this confuses me. I realize there is some threshold, stock @25mph, that activates the CC abilities. But clearly the CC module is aware the vehicle is moving to some extent. Is it getting this (under 25 mph) information from the VSS or another source? I would like to figure out if my Hall Effect Sensor is wired correctly, but maybe needs some type of additional part, or maybe my signal from the magnet is not strong enough. Anyways, any additional data to point me in the right direction would be a big help.

 

[FranceJohnson]

I forgot about this thread, but I wanted to follow up with it. Several months ago I had my father-in-law give me a hand with soldering the sensor. He did the same process as I used, but instead used a small piece of circuit board to solder to. I am not sure if the issue was that I am a not very good at soldering so I overheated the chip possibly, but it works great now. I think it hits the minimum somewhere around 25-30. Works exactly like it should. I have about 6 or 7 more of those sensors laying around. 100% worth the money, even if you have to find someone to give you a hand.

 

[veiloctane]

I forgot about this thread, but I wanted to follow up with it. Several months ago I had my father-in-law give me a hand with soldering the sensor. He did the same process as I used, but instead used a small piece of circuit board to solder to. I am not sure if the issue was that I am a not very good at soldering so I overheated the chip possibly, but it works great now. I think it hits the minimum somewhere around 25-30. Works exactly like it should. I have about 6 or 7 more of those sensors laying around. 100% worth the money, even if you have to find someone to give you a hand.

I'm interested in these sensors if you still have them around I would like to attempt to repair my cruise control

 

[concretejungle]

As a follow up from my earlier post, i have continued to have intermittent cruise control issues. They seem to be rare, but occasionally they will pop up.

So far i have been able to "fix" my issue mostly by jiggling the wires that lead to the CC module in the engine bay. Then, i tracked down the actual plug connections that plug into the CC module. When i disconnected them they were heavily corroded. I happened to have a can of electrical connection cleaner in the truck, so i sprayed liberally on the plug connections, wiped them down and repeated a couple of times. That seemed to do the trick. So far so good.

So, check your connection plugs and see if they are making good connection.

 

[FranceJohnson]

I'm interested in these sensors if you still have them around I would like to attempt to repair my cruise control

PM sent.

 

[sea bass]

Low brake fluid has nothing to do with your cruise control not working

 

[91 AV Pig]

If your brake fluid is low, it will cause a brake light to come on that will effect your cruise control. Sometimes the brake light can be very faint and hard to see. This has not been witnessed first-hand, but comes from reading all threads related to cruise control as I tried to fix mine. This was before these HE sensors were tried, which I have to give a go...

Anyone still have extras for sale?

 

[sea bass]

again low brake fluid has nothing to do with your cruise control not working

 

[91 AV Pig]

I may have misstated the effect, but see the note below...

from Cruise control not working. Where is the fuse?

Low brake fluid will keep the CC from setting a speed, but it won't completely disable the CC system. When you activate the CC ECU, you should still see a green CRUISE lamp on the dash. This is letting you know that the CC ECU is functional.

There is a CC diagnostic somewhere that I need to dig up, but the ECU sounds like it's not getting power to me. I'll poke around when I get time today.

 

[sea bass]

On a 92a95 and a 97 I tested where I disabled the brake warning light on purpose via the master cylinder the cruise control still worked 100% ,that's what I found.did you run any tests yourself or did you just hear it from somebody

 

[jonheld]

again low brake fluid has nothing to do with your cruise control not working

Well, that depends on how low is low. If the sensor in the cap triggers the brake lamp in the dash, the CC will not set a speed. The brake lamp circuit is what cancels the speed setting. THis works when you step on the brake pedal enough to illuminate the brake lights in the rear, and when you slightly pull the handbrake to illuminate the brake lamp in the dash. If the sensor in the cap is faulty, which is very common, the brake lamp can dimly illuminate and that will keep the CC from setting a speed. Disconnecting the cap sensor is an easy way to tell if this is the issue.

 

[IanB]

On a 92a95 and a 97 I tested where I disabled the brake warning light on purpose via the master cylinder the cruise control still worked 100% ,that's what I found.did you run any tests yourself or did you just hear it from somebody

Does disabling the master cylinder brake warning light cause the signal to be on or off all the time? I'm guessing off, which really wouldn't prove your point...

 

[jonheld]

Does disabling the master cylinder brake warning light cause the signal to be on or off all the time? I'm guessing off, which really wouldn't prove your point...

When you unplug the reservoir cap, the brake lamp in the dash won't illuminate due to low fluid level or due to a fault in the sensor. The fact that the brake lamp is not illuminated will allow the CC to function properly, assuming the rest of the system is good.

 

[sea bass]

I did not just unplug the sensor wire . I simulated a low brake fluid situation which closes the circuit

 

[sea bass]

My point is I simulated the exact same conditions as a low brake fluid in my 92 and my brothers 95 and 97 what I found is the cruise control still work 100% I don't remember if I tried to increase speed or not with the low brake fluid that may be true because a couple years ago I had some cruise control problems and I wanted to find out if I had it it had anything to do with low brake fluid it ended up being my speed sensor on the transfer case

 

[jonheld]

I did not just unplug the sensor wire . I simulated a low brake fluid situation which closes the circuit

Well, without details as to what you did I'm not going to bother guessing.
I will say again, that the CC ECU relies on the 2 brake signals, one from the rear brake lamp circuit, and the other from the dash brake lamp circuit. Either one of these will cancel the set speed or if constant, will prevent a speed from being set. SO if whatever you did prevented the dash brake lamp from illuminating or somehow interrupted the current path to the lamp, or from the lamp to the CC ECU, then, yes, the CC would function normally. EXACTLY the same way that unplugging the reservoir cap prevents the dash lamp from illuminating when the sensor is low.

If the speed sensor was in fact faulty, your green CC dash lamp should have blinked an error code and disarmed the system letting you know that there was a problem. This would have happened when you tried to set a speed on the stalk. The system would remain down until the next time the car was started.
There is an onboard CC diagnostic procedure in the FSM that outlines this, but in reality, there's only 1 main point of failure and you found that.

 

[sea bass]

Well thanks for the good info John I did my troubleshooting after my cruise control was all fixed like I said I had heard about the brake fluid level and I wanted to see if it cause the cruise control to not work I don't remember everything it was a couple years ago