1996 Pontiac Sunfire Driving Down Highway Cruise Control Will Only Sometimes

all emission systems test are complete and there is no check engine light and no stored codes. I have very smooth readout on TPS sensor from 0% to 100%

the only info I can up with is that it has to have the correct tps voltage, brake light switch open, vss constant.

OPERATION
The module will interpret the position of the servo, the position of the control switches and the output of the speed sensor. In response to these inputs, the module electrically signals the opening or closing of the vent and vacuum solenoid valves in the servo.

The module is mounted on the dash support bracket at the right side of the steering column, but is integral with the ECM on some models with certain engines.


i see no way to test with module without replacing it.

Roy

There is actually a cruise tester box you use for diagnoses that's plugs in between the cruise model and the harness that plugs into the cruise model.They sell the boxes on eBay used for pretty cheap. The box lights up on all the cruise input States. Some of the boxes actually allow you test the cruise control in the shop by stimulating vechile speed.

in reply to Roy

thanks for your quick help, i do not believe there is any vacuum within the cruise control system at all unless its reading the MAP sensor. When you say change the module do you mean the module that has actually pulls the throttle plate with the cable or is there another component like you said inside next to steering column that i overlooked.. Or do you you mean replace the entire PCM/ECM

the brake light switch i would rule out since i do not hit the brakes at all between 3rd and 4th which cruise will stay engaged as long as id like it to in those gears. there is no information from this transmission to the pcm on which gear im in other than relative RPMS to MPH. The only 2 plugs on the trans is VSS and reverse switch its very basic. The VSS wiring has a new pigtail also


In response to Saturntech9
is the KENT-MOORE J-42958 the one i should shoot for? if that is the right one it could be used into the 2000s because the somewhat newer obii cars still have the same style cruise servo


thank you for the replies still need a little more information

I will look up if that is the correct tool number when I get home.I am out of town right now and will be back in town sometime today.The cruise box tools are the best ways to trouble shoot cruise problems I have used them many times with great success.

I couldnt find any mention of a cruise module box for testing in my mitchel ondemand it tells me about using apin out test and using the tech1 scan tool to run a service bay test.I posted all the cars your cruise module fits.

This car does not have a tech 1 port it has OBD II port for emissions...i also own a 1995 it also has an OBD II port and does not have an OBD II computer... So i will have to use the Tech 2 and try what you recommend. The part number you posted i have replaced already with another DELCO Servo with the exact same results, also with the switch on the column...

Do we no longer think that this cruise tester will work it seems like it has all of the correct pins and connections neccessary and it was used and created in the correct era for this vehicle

im thinking there is interference with the VSS either with shavings from the last transmission or in the wiring.

The tech 1 is a gm scan tool used before the tech 2 came out it was used on obd 2 cars.It is possible that cruise tester may work I am just saying from the info on Mitchell on demand it doesn't list a cruise tester.You maybe correct about the vss signal/sensor or shavings.I was wondering if it thinks the transmission is slipping or vss signal gets lost long enough to disable the cruise control.

Thanks for the reply, i will find out tomorrow if my uncles tech 1 scan tool will hook up to this car. He uses it on his Formula Trans Am 1991 so its definitely a Tech 1.

Some other miscellaneous information is this problem seemed to have happened right as the synchronizers for 2nd and 4th were lost on a long road trip not sure of the cause on that one but have a new rebuilt transmission the only common denominator is the VSS as its the only information output this transmission has. The leads look like they are exposed right as they go to the connector from the coil inside the sensor (attached pic). upon taking it out of the bad transmission one can only imagine how many shavings were attached i was pretty shocked. blew it out with an air gun but was nervous about the micro sized gauge wire for the signal so i didnt want to blow a lot of air close up or try to scrub the sensor.

upon installation of the new transmission clutch and flywheel everything is perfect except for the cruise problem which happened on the road trip originally. when engaged in 4th gear now it will resume, set, accelerate, and coast as normal but i dont recall testing at 75mph in 4th gear, like i attempt to set and accelerate in 5th gear will have to try that, maybe the pulses per mile are harder to pick up, compared to going 45 or 50 when not on the interstate when i road test 4th gear.


thank you for your response i hope to follow up with any outcome as this has been going on since October and has really tested my skills. have never encountered anything like this.

i still wonder if its a good investment to have the cruise module tester box as you are right about them being cheap thank you saturn for your input you are the most help of any of my colleagues of techs so far

As long as his tech 1 has the odb2 set up with the correct cartridge.So that's not the oringal transmission? What year did that transmission car and model did it come out of?Is there a vin number on the transmission?

the transmissions arent vin matched they are just simply MJ1 or MK7 i believe this vehicle uses the MJ1 i will attach many pictures of the information i have collected

This is the 3rd transmission since Most recent ownership and it was from trans star corporation in Ohio they are a big chain of transmission rebuilders. They don't sell to the public. That's all that one of my buddy uses for a transmission supplier not jasper or any of the other local chain builders. It was vin matched also. pictures below

whats left of the tag in one of the pictures is off the old transmission and is another code used by GM for the transmission for that year/engine combination all the other pictures are of the shift forks and wont do much help to this as it was for the old transmission

sorry correction they are technically vin matched but the real code is MJ1 or MK7 apparently the MR8 code on the tag is the codes suppliers use on file for these early sunfire transmissions. MR8 transmissions come back as Isuzu built as is the mj1 but i do believe the bell housing is different there for it must be an MJ1. This would obviously fall back on TranStar but i talked with them and they assured the vin pulls this transmission. also as the tag states on the box. thats why i chose to attach that pic. Ive already been down that road and there are certain things that wouldnt line up if it was the wrong transmission.

also another reason why i mentioned this problem before the change of transmissions... must be electrical.

the VSS reads like an ABS sensor on the differential in the case therefor gears do not affect how the VSS gets its signal other than how fast the diff is spinning and how fast pulses per mile should be getting signal

this is how ive come to understand it in on paper and in my head. just not sure where to turn next.

The reason I asked about the transmission is because I worked for Saturn for many years and the transmission on the SL1 and SL2 will bolt up and work on both cars drive down the road.But the gear ratios are different and will cause issues because of it.Which engine do you have?

2.4L LD9 Twin Cam the one that every one calls a night mare but i disagree i think its a well built motor just a little outdated for ignition. anyways if what i need is a recalibration of my PCM i would be willing to bite the bullet and go to the dealership for a retune of the PCM. The difference between the MK7 and MJ1 is supposedly only the bell housing but it is built the exact same. but im sure there can be some other variables that go beyond the knot heads on the forums that say some of the statements the claim.

unfortunately i do not have and Ins with the techs at my local GM dealership even with as big into Chevy my family is the only connect i have is the parts desk guy and i doubt he could get me a discount re calibration of the PCM. I do not have a subscription to the flashing website with the files for programming PCMS but i have just about every scan tool imaginable for GM available to me all the way to the VCI just prefer the tech 2 above all others.

Its the only one other than the Snap on scanners that i have a lot of practice on. Unfortunately I would only trust GM to do my PCM unless theres something that i over looked with anything that i have access to.

Oh the quad four not a big fan lol especially doing a water pump lol.I like the eco techs they at least have a holding tool to hold the chain when changing the water pump.Have you tried to see if your speedo. Is correct by using a portable GPS that displays vechile speed on it?That would tell us if the computer was reading the correct speed from your transmission.Also why don't you change your vss connector at least with a used one if the wires are frayed at the connector?Wouldn't hurt to do that if it was my car I would change the connector.

haha i hear ya im about to do some top end work if i can fix the cruise while its not being driven and do the water pump and everything else this engine is known for is next on the list (head gasket preventive maintenance)! anyways thats another day and something that will go smoothly unlike this has gone so far. i can use a speed trap set up in my town on the next test drive or compare scanner readout like you said with GPS information or even have someone ride next to me.

about the speed sensor wiring...im sorry if i confused you, the speed sensor pigtail is new running up into the engine harness. its the speed sensor itself that had the leads exposed to the fluid inside the transmission as well as the shavings thats why i got that angle of the speed sensor picture to show you what i was talking about the red/orange/copper color is what looks to be the stuff they wind coils with thats how thin it is. everyone says the leads should not be exposed outside the sensor but i went to the parts store and just showed you a picture of how the wires are exposed on the inside of the transmission on a NEW sensor.

i havent checked for more shavings since the transmission was installed considering there shouldnt be all that much with a new trans installed...i have not exchanged fluid yet on the new trans as it hasnt even been 1500 miles.

i will get back to you about the tech 1 attachments and possible test drive after i fill it full of coolant since it likes to leak out since its been sitting since october after the new trans was installed. i cant wait to finally put the water pump in to make that part easier.

when it rains it pours. again i have all the other stuff under wraps its the cruise that is really posing the big question!

Yeah have fun with the water pump lol I have replaced those before on that engine.Keep me posted on what you find.

it wont be too bad with the head off the engine when spring rolls aroun haha...

anyways looks like i spoke too soon he said it is an OTC scan tool i swore it was obd1 for our custom TPI corvette but apparently the computer in that car virtualizes a 1996 corvette pcm so no dice on the TECH1. He also said hes missing a lot of cartridges and who ever sold him the scanner didnt give him his 1700$ worth... id say so...

should i look to see if the tech 2 offers the same diagnostic function or is finding a tech1 the only way out...

i bought the cruise tester box also maybe that will work and if not ill hold on to it for a while or resell it

do you use mitchell on demand9? do you have any all data information...i also have access to all data but only when i swing by my friends garage. Thanks for the help so far,

would you know if the tech1 test would require a road test or the car to be on the lift running through the gears?

thank you again this is a big goal of mine to get the bottom of this i have a feeling i should just buy all switches, clutch, and 2 brake switches to rule those completely out...my transmission friend said he would hook me up on a new speed sensor as he feels thats probably the problem...


shouldnt be this hard! haha

Yes it only shows the tech for diagnoses it doesn't show a trouble tree for cruise only stays on for a few ?seconds.The closet is cruise inop which isn't the case.Let's wait and see if that cruise tester works so we can see what's going when it kicks off.Have you tried checking the speedometers accurate? Also I only have Mitchell on demand.Can you check and see what all data has for diagnoses?

Good news....i think! :/

So the cruise tester came in and in a leap of joy I tore it open and got to work...Read the manual which i will recite the full passage for a certain part of the test procedure. i was working quickly part because im pumped to conquer this problem and part because it was raining! Anyways everything checked out until i got here:

Exerpt from tool:
" TESTING THE STOP LAMP SWITCHES (BRAKE/CLUTCH LED)"

" With the tester still connected between the cruise module and the harness, depress the vehicles brake pedal and observe the testers display. The BRAKE/CLUTCH light on the tester should TURN OFF and the LIGHTS LED should illuminate when the brake or clutch pedal is applied. The alternating BRAKE/CLUTCH and LIGHTS lamps on the tester indicate the proper opperation of the vehicles dual brake switches. If these tester lights do not illuminate when testing possible causes can be faulty CRUISE RELEASE SWITCH, BRAKE SWITCH or possible short or open between switch and cruise module."

okay now it took me 3 times to read that because theres a lot of variables at play here.

RESULTS: LIGHTS led ILLUMINATED without brake pedal depressed. Brake LED Goes out LIGHTS Stays lit when pedal depressed. i have confirmed the brake lights work left right and highmount and they are NOT illuminated when pedal is released.

so as strange as this is to me i cant imagine this causing a problem in only 5th gear

so here is what ive found (attachments) The ones labeled cruise release come in a pair and look like the clutch switch and one swich on the brake pedal

there looks to be a total of 3 switches in the vehicle

2 SEPARATE switches on the brake pedal and one on the clutch

the word "separate" is capitalized because theres actually 3 switches on the brake pedal. One of the switches has two connectors in which only one is hooked up; i would imagine the one that is not hooked up would be for an automatic trans possibly. (attachment for brake switch illistrates what im talking about)

I have supposedly have all 3 switches in a cart incase this is resulted as the problem
( if the one "cruise release" includes 2 in a pack as customer support assured me.)

sorry for the huge novel sorry if its hard to follow. if any part of it is confusing let me know and i will re phrase!

ADDITIONAL:

I proceeded with the test after the BRAKE CLUTCH SWITCH test and confirmed the servo completely retracts the ribbon to WOT and holds it there until I hit "BRAKE" button which proves the module all the way to the throttle body is A-OK. other tests that passed were cruise activation switch: SET/COAST and RES/ACC and ON/OFF...coincidence or not i was not willing to jack the car up in the rain and leave the tool possibly exposed to water to test and check VSS so thats the only test i believe i did not do and will have to wait.

That cruise tester is pretty nice huh?I loved using it when I worked at the dealer.Glad to hear that one worked on your car.So one of the brake switches were not reading correctly on the cruise tool?

i have no idea i was hoping if you read all that and came up with the same answer id imagine maybe one of them is messed up thats why it says "LIGHTS" when the pedal isnt depressed and is only supposed to illuminate LIGHTS when brake lights are on? i guess its no sin to buy 27$ in parts when it very well may be the cause (all 3 switches)... i will verify everything again tomorrow just to triple check. is there any way like if maybe i unplug the switches and jump them with a paperclip or leave them untouched that i might be able to mock if the switch was to work correctly? maybe it would help further diagnose the cause...and also i guess nothing will tell the truth until i can get a reading on the vss!

i think i read that right out of the instructions...but this tool is so awesome!

You could jump it so it read the correct state the important states are the ones without the pedal pushed because if those aren't correct that will cause the cruise to shut off while driving and not touching anything.Another thing I have seen cause cruise control to shut off while driving or be inop all together is switches out of adjustment. You could also have someone drive the car in 5th gear with the cruise on while you sit in the passenger seat watching the cruise box and all of its lights.That way you can see what happens when the cruise control shuts off?

The module is under the hood against the firewall so it won't be possible to try it that way I just figured i would try it on the lift. It will kick the abs light on but maybe I could see what's happening that way maybe... The not reason why I could imagine "LIGHTS" stays illuminated might be because it has led brake lights so theres no rsistance as if there is a filament installed. but it would be easy to Substitute a socket that dangles or to wire an inline resistor between leads to trick the computer to thinking original bulbs are in place. The worst part about this is that all LEDS in the rear were installed after this problem took way and after the transmission installed which is why I want to dismiss this theory all together.

I still haven't had a chance to check VSS, but according to the manual it has to be going 25 mph and I would imagine at this state VSS should have a solid light.

Brake and clutch sensor are working every time and are adjusted properly . I found a flow chart on autozone that said if those switches are too tight? That it will fail?

At any rate when testing the module again when I would over ride the cruise it would keep pulling the throttle body plate little by little until it was open fully and if you hit set coast it would start to let ribbon out and either stop half way or go all the way out... Not sure if this is part of the test or not but I wasn't sure upon observing closely. This result happend with 3 separate modules all off of different year cars same part number!

Hopefully. Can get some input on that!

I have seen where if the brake light switch and the cruise switch the two on the brake pedal are not adjusted evenly it will case the cruise to work erratically.

Well well....I am sorry for how long I havent provided any updates but I am still searching high and low for this problem. I have now searched every menu of the Tech2 only to find that the tables for revolution per mile cannot be adjusted... I have done a lot of searching and have come up with some similar problems close to mine on a GM car and it so happens to be a saturn.....

Supposedly there are swaps that guys are doing out there for the final ratio that will lower rpms in 5th gear... Well, i have sworn even to the transmission guy that my RPMS in 5th are a tad lower than the last 2 transmissions but i agree with him and everyone else with the answer that all 5 speed internals for the sunfire and cavalier are the same so i cant imagine there really being a change it might just be my mind. I still need to verify the speed even though i still have stock tire size.

I have thought this through to understand that changing the speed sensor will not allow the computer to understand any better that the car should engage cruise in 3rd through 5th gear something else has happened to engage in 4th and 3rd flawlessly and very smooth but in 5th its erratic and not consistent.

which says something of installing resistors between pins...im still reading the whole thing as the thread is rather long but this could work... I still have not tested VSS on the lift with the cruise tool but as soon as the snow and ice go away that can be done quickly

I have checked every DTC which was only VTD and loss of data a very long time ago and has had a lot of completed drive cycles since. These cruise systems are heavily reliant on the tables coded in the PCM.... please let me know if you have come up with any other ideas... the brake and clutch are working correctly according to the J tool and Tech2 and Solus Ultra AND snap on verdict not that i thought any of them were wrong those are just some that have been used so far. Should i really be looking to find a Tech1 still?

Thanks for all the help I know we can solve this! I also have found a few flow charts for Cruise if you read through them please let me know if you think this is a good basis with the J Tool! ill attach the images below...ill only attach the first 2 of the 6 i have so its not infringement or anythingl ike that

well i appologize for sending that link i read a little too fast and it looks as though its only for code setting of Cruise control...i wish i had a code to read from my cruise control so scratch that idea until i read further! not totally sure why this is so hard nothing has changed unless there is a scrambled data from the VSS im totally dumbfounded!

I wouldn't go out of your way to get a tech I suggested it since the trouble used one.If the cruise worked fine before the transmission replacement makes think about the transmission may be some how effecting the transmission. How I don't know you still haven't made sure the speedo is correct?