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STICKY: Cruise without the ECM.. The Answers !!!!

Posted By: 85SSMan

STICKY: Cruise without the ECM.. The Answers !!!! - 05/05/04 11:41 PM

Here is the scoop, I recently rebuilt my engine and like many others took out the computer harness, BUT, here is the difference, From what I gather alot of us are just pulling the sensors, and not cutting out the harness at the computer like I did. So for those of us that have cut the harness, and now have no Cruise Control fear not!!! The only thing that we need to fix is..

Find your buffer box, it is a small green box located behind the stereo(drivers side) there is a total of 7 wires coming out of it. Three are together coming out of the bottom (RED, GREEN, BLACK) these wires run to the VSS on the back of the speedo, GREEN is 12V, BLACK is Ground, and RED is the SIGNAL to the BUFFER.

Next you will find two harnesses on the top off the buffer box, one SINGLE YELLOW wire, this sends the signal to the Cruise Control Module, also there is a 3 wire harness, this is where the BIG PROBLEM lies, PINK/W BLACK STRIPE wire is your 12V to power the VSS, BLACK/W WHITE STRIPE this is the GROUND, THIS WIRE USED TO GROUND TO THE COMPUTER HARNESS, THAT IS WHY YOUR CRUISE WONT WORK!!! CUT THIS WIRE AND GROUND IT WITH YOUR STEREO HARNESS. NOW YOUR CRUISE SHOULD WORK. Also has a brown wire, this can be ignored, it is the VSS signal to the computer.

IF this doesnt fix your CRUISE after you have removed the computer harness let me know, I have been through this entire system and know it pretty well now, I am positive that I can diagnos your system, just try to be specific with your problem, and what you have done.

beer

Chris
Posted By: jzajac1

Re: Cruise without the ECM.. The Answers !!!! - 05/06/04 02:23 PM

Good info, thank you
Posted By: Draxx'87SS

Re: Cruise without the ECM.. The Answers !!!! - 05/06/04 11:04 PM

Posted By: 85SSMan

Re: Cruise without the ECM.. The Answers !!!! - 05/07/04 12:22 AM

you guys should of seen the happy dance I did when it worked, felt as good as the first time the engine ran.

Chris
Posted By: MonteC

Re: Cruise without the ECM.. The Answers !!!! - 05/07/04 12:37 AM

ill have to try that and get mine working.

why did you have to CUT your computer harness out? i pulled the whole thing out, without cutting any wires.

i actually ran my sub power wire through the hole it left and used a piece of hard plastic to seal the rest of the hole up.
Posted By: Draxx'87SS

Re: Cruise without the ECM.. The Answers !!!! - 05/07/04 01:28 AM

Posted By: 200kSS

Re: Cruise without the ECM.. The Answers !!!! - 05/07/04 03:51 AM

I'll print this out and try it out on the Malibu. Right now I've got the computer and complete harness laying on the floorboard just so the cruise will work.
Posted By: 85SSMan

Re: Cruise without the ECM.. The Answers !!!! - 05/08/04 02:02 AM

200kSS, that should work for you if not let me know and I will try to help you out.

Quote:
why did you have to CUT your computer harness out? i pulled the whole thing out, without cutting any wires.
i had to cut all the wires that are in the dash harness that went into the engine compartment. The computer harness did unplug, I just thought I would rip it all out, but now starting to regret that.

Chris
Posted By: 84montecarloss

Re: Cruise without the ECM.. The Answers !!!! - 05/11/04 06:40 PM

thank you. will try this after i put all the stuff back on...took it off cause it diddn't work. thank's again u are a good man
Posted By: chevelle502

Re: Cruise without the ECM.. The Answers !!!! - 05/11/04 09:26 PM

this should also become a question on the FAQ section, very good info here.
Posted By: Draxx'87SS

Re: Cruise without the ECM.. The Answers !!!! - 08/14/04 01:13 AM

Posted By: Z65_Paul

Re: Cruise without the ECM.. The Answers !!!! - 08/14/04 02:00 PM

I just added the original info to the SS FAQ Electrical section. Thanks for the reminder.
Posted By: speeddemon

Re: Cruise without the ECM.. The Answers !!!! - 08/14/04 02:52 PM

Not to start anything but why not use the 78-80 style cruise that doesn't have the ECM?
Posted By: 85_SS

Re: Cruise without the ECM.. The Answers !!!! - 08/14/04 03:24 PM

Quote:
Originally posted by speeddemon:
Not to start anything but why not use the 78-80 style cruise that doesn't have the ECM?
It's probably a matter of using what you have - and if I am reading that right, it is as simple as manually grounding one wire that the ECM used to ground \:\)
Posted By: Draxx'87SS

Re: Cruise without the ECM.. The Answers !!!! - 08/14/04 04:45 PM

Posted By: baaboo

Re: Cruise without the ECM.. The Answers !!!! - 08/18/04 02:16 AM

How about this question for the experts, that I'm NOT! I put a TPI with a 7730 computer in my car. I needed the 4-pulse VSS. Any idea what is a good cruise control to use in the Monte body with the TPI computer and harness?
Posted By: 85SSMan

Re: Cruise without the ECM.. The Answers !!!! - 08/22/04 04:19 AM

Not for sure, but I would think that if you could get your vaccumn solenoid from the stock monte cruise over to a fender, and a detent cable from the vaccumn solenoid to the TPI unit, you should be able to keep the stock cruise from the monte.

HTH

I will know more when I finally get an LT1 for the beast. But I think I will try to keep the Stock cruise system. Everything else under my hood is already Camero.

Chris
Posted By: realsurfer88

Re: Cruise without the ECM.. The Answers !!!! - 08/21/05 03:20 AM

before i start getting out blade and hacking up a perfectly good harness, i should ask if i can run this setup, the re grounded wire, on a ss with the ecm still in use. im pretty sure that everything else on the setup is perfect , vac lines, motor connector, everything, but i just want to know if this has the same effect on an ecm car. thanks guys
Max
Posted By: juangomez22

Re: Cruise without the ECM.. The Answers !!!! - 06/10/08 09:24 PM

thanks 85SSMan i appreciate this great info. i think i had already read this somewhere here on the forums but regardless where i read it. i appreciate you posting this great info. thanks juan...
Posted By: spudmanmike

Re: Cruise without the ECM.. The Answers !!!! - 06/29/08 11:10 PM

Originally Posted By: 85SSMan
I will know more when I finally get an LT1 for the beast. But I think I will try to keep the Stock cruise system.


If you plan on going with a 4L60E or T56 where there is no mechanical speedo drive, its easy using a cruise control drive from an Impala or Caprice and the LT1s PCM. I think its a half dozen wires all together. I'll be trying this later this year with my car, which did not have factory cruise.

It is completely feasible if running the mechanical speedometer to use the stock system as there is no hookup to the stock ECM, but that cruise assembly with the vacuum actuator is PLAIN UGLY!!!!!!
Posted By: 345HP87SSAC

Re: Cruise without the ECM.. The Answers !!!! - 10/12/08 05:42 AM

Thanks I will try it.
Posted By: bradleyls103

Re: Cruise without the ECM.. The Answers !!!! - 12/04/08 01:30 PM

Originally Posted By: chevelle502
this should also become a question on the FAQ section, very good info here.


I agree!
Posted By: Mikey340

Re: Cruise without the ECM.. The Answers !!!! - 12/31/08 10:56 PM

Originally Posted By: realsurfer88
before i start getting out blade and hacking up a perfectly good harness, i should ask if i can run this setup, the re grounded wire, on a ss with the ecm still in use. im pretty sure that everything else on the setup is perfect , vac lines, motor connector, everything, but i just want to know if this has the same effect on an ecm car. thanks guys
Max


Pretty much same question.
Mine is a 1985 body with an 87 motor and ecm. Cruise doesn't work have vacuum but no power at the connector on the side of the diaphragm?
Mike
Posted By: WaSSted

Re: Cruise without the ECM.. The Answers !!!! - 02/17/09 07:54 PM

Not only is my ECM gone, I also replaced the stock speedo with a mechanical Autometer speedo.
In 2000 I purchased a VSS form jegsthatrun with hopes to reinstall my cruise and never got around to it. Turns out I got the wrong VSS so 9 years later I called JTR and they are sending me the correct parts for my VSS.

My question, how do I wire it up? JTR told me that one wires goes to ground and the other goes to the VSS input. Where is the VSS input? The Haynes manual that I have is absolutly no help. So I managed to borrow the 1988 Monte Carlo electrical services manual (yes, I scanned every page into PDF format wink).

So if you are like me and have aftermarket gauges and no ECM, you will need to ground the wire from the buffer as mentioned in previous posts and in the FAQ.
In addition, the VSS from JTR has two wires; one goes to ground, I will go into more detail on the VSS wire.

Now this is my theory, please correct me if I am wrong:

From what I have learned, there are three wires in our cars that go from the buffer(green box) to the back of the speedo (where the factory VSS is located). You have a red positive, black negitive and green is the VSS signal, correct? I believe the green wire is what you need to splice the JTR speed sensor into.

I will not know if this actually works until I receive my parts from JTR and install my heads. Maybe this weekend I will know if my theory is right or wrong.
Posted By: WaSSted

Re: Cruise without the ECM.. The Answers !!!! - 02/26/09 02:59 PM

Ok, my cruse works! Yippee!

I got the VSS from JTR last weekend and installed it. It did not work at first, i hooked it up to the green wire coming from the stock VSS behind the speedo going to the buffer. The buffer is not required for this VSS to work, so I pulled the yellow wire from the buffer, cut the end off and wired it to the VSS, and PRESTO!
Posted By: Phoenix

Re: Cruise without the ECM.. The Answers !!!! - 03/18/09 05:21 AM

Originally Posted By: WaSSted
Ok, my cruse works! Yippee!

I got the VSS from JTR last weekend and installed it. It did not work at first, i hooked it up to the green wire coming from the stock VSS behind the speedo going to the buffer. The buffer is not required for this VSS to work, so I pulled the yellow wire from the buffer, cut the end off and wired it to the VSS, and PRESTO!

Congrats!!! This is one of my favorite threads on the entire board for being very good rare info. I used the info from this to wire my '87 for cruise several years ago, but still don't have it running. My issue was complicated initially by needing an inline speed sensor, but the primary reason I still don't have it working is because the cowl sealing pan I installed didn't allow room for the vacuum accel control...and so I need to find a smaller one. But, after almost slamming into a highway divider while hydroplaning a couple years ago, I've also had second thoughts about having cruise on that car at all. This is a great thread; glad to see it is sticky'd.
Posted By: 06mcss

Re: Cruise without the ECM.. The Answers !!!! - 06/11/09 03:33 AM

I too have cut the computer side of the harness out of my monte, and I want to get my c/c working again. but I have another question, I remember when the original engine was still in the car. there was a few vacumm lines coming from the passenger side next to the fender what do those vacumm lines connect to? ...tia...Bill
Posted By: Fireball69

Re: Cruise without the ECM.. The Answers !!!! - 06/11/09 03:48 AM

Tex,I believe they went to the MAP or trans lockup,I will look at my 88 tomorrow.My business is slow so Im doing a partial restore on mine,may post some pics if Ican figure out how,
Posted By: 06mcss

Re: Cruise without the ECM.. The Answers !!!! - 06/11/09 04:50 AM

fireball, that would be great. maybe some pics if you could, just to see where all the vacumm lines connect and where they originally come from...tia...Bill
Posted By: Fireball69

Re: Cruise without the ECM.. The Answers !!!! - 06/14/09 04:04 AM

Sorry about not getting back with you,my body man has more parts on the hood than underneath or inside,anyway maybe I can get my son(s) or wife to show me how to post pics.Guess you can tell I'm an inexperiencd blogger.
Posted By: irkk1

Re: Cruise without the ECM.. The Answers !!!! - 06/19/09 12:04 AM

what about the overdrive torque converter lock up ..or do you just use one of those switches.. i dont like the switch idea
Posted By: 06mcss

Re: Cruise without the ECM.. The Answers !!!! - 06/29/09 03:38 AM

does anyone have a pic or diagram of the vacumm lines used for the cruise control. I have taken out the computer side harness, and need to know how or see how to rehook up the vacumm lines again....tia...Bill
Posted By: 06mcss

Re: Cruise without the ECM.. The Answers !!!! - 06/30/09 02:23 AM

anyone help please...Bill
Posted By: ss4ever

Re: Cruise without the ECM.. The Answers !!!! - 06/30/09 02:28 AM

I don't have a diagram but there are two lines that go to that style diaphram, small and large. The large comes from the switch under the dash and should come out with the wiring harness. The smaller hose will come from the manifold and will work best if you have a small vacumme canister Tee'd into the line before it gets to the diaphram.

Randy
Posted By: Black Sunshine

Re: Cruise without the ECM.. The Answers !!!! - 06/30/09 02:32 PM

Is it possible to use the Monte cruise control when switching to an LT1 (or any other newer motor for that matter)? Would I just have to get the conversion box to get the speedo working again and then the cruise would work like normal? I need to know if I can leave the cruise control module in the donor Z (its rather large) or if I need to rob it.
Posted By: 06mcss

Re: Cruise without the ECM.. The Answers !!!! - 07/01/09 04:23 AM

Randy, I got all the wiring and the large vacumm line and the ball canister on the passenger inner fender for the diapham. the lines I am talking about, if I remember correctly. two small thin vacumm lines came from the passenger side fender, close to the antenna connection area. or is was them lines for something else?...tia...Bill
Posted By: ss4ever

Re: Cruise without the ECM.. The Answers !!!! - 07/01/09 05:14 AM

Those two lines are for the HVAC system, one supplies vacumme to the tempurature control and the other comes from the temp control to shut off the heater core while on MAX AC to help keep temps low inside the car.
Posted By: drb930

Re: Cruise without the ECM.. The Answers !!!! - 11/14/09 06:28 PM

I have all the Cruise Control Diagnosis Diagrams on my computer.
If someone will tell me how to post them here I will put them up.

Had to complete re-install the Cruise Control in my ElCo that was removed and it also now is running a TPI Setup.

Thanks,
Dave
Posted By: Sherdep

Re: Cruise without the ECM.. The Answers !!!! - 04/28/10 02:51 AM

Good thread for Info - here is a question - the vac diaphram that is on the drivers side fender well just in front of the brake booster - can someone tell me what it hooks to and post a picture cause mine is missing what I think it either a spring or not exactly sure and now that I have done the computer delete I will need to get this working as well - a [icture belw of what I am looking at and am not sure what it hooks to
Posted By: 06mcss

Re: Cruise without the ECM.. The Answers !!!! - 06/11/10 05:26 PM

I have a question about the c/c w/o ecm. I have read the article concerning the green box under the dash and the black w/white stripe wire as ground. my ? is, if I cut this wire at the green box, I will have two black wire from it. which wire gets connected to the radio ground? one wire will come from the green box and the other wire should come from being connected to the turn signal lever..tks for any help...Bill
Posted By: 06mcss

Re: Cruise without the ECM.. The Answers !!!! - 06/21/10 06:25 PM

I have grounded the black w/white stripe from the green buffer box to the ground on my stereo and still have no cruise control. is there something else I am missing? tia...Bill
Posted By: jwat

Take out Computer or Fix it? - 09/03/10 03:57 AM

So just learning about my '88 Monte, I discovered I have an issue. My computer is still installed and functioning as far as through the distributor. It is currently disconnected from the carberator. When I plug it into the carb, it instantly dies. As much as I can adjust the idle screw, it will not start up and idle with the harness plugged in. I read a post on here about taking the computer out and replacing the intake, carb, and distributor, as well as adding the toggle for the tranny and also putting in an ignition(coil) with the new non cc distributor. This sounds like quite the project. This car is my everyday driver. What else can I do to temporarily get around this issue. I can't keep driving it like it is. It is GUZZLING fuel almost as fast as I put it in. Do I need a new computer? Or tps? Or mcu? Help!
Posted By: 87ChooChoo

Re: Take out Computer or Fix it? - 09/05/10 05:29 PM

JWAT, sounds like your carb needs a rebuild ( or buy a rebuilt CCC carb). Without the computer controlling it, the carb goes to full rich all the time. Gas Guzzler.

It is probably the Mixture control solenoid. Plug both of the electical plugs into the carb, and turn the ignition key to on. You should hear some very fast clicking from the carb. No clicking, then the MCS is probably bad. Unplug the carb and test the MCS with an ohm meter. If it shows "open", then the MCS needs replacing. The other part that can go bad is the TPS (Throttle Position Sensor). Ignitnion on, you should have about .5 volts across the black and blue lines.

If you are not comfortable with rebuilding a CCC Carb, best to consider a rebuilt. Search this site- you will find many recommendations for a rebuild. Do not buy one from your local auto parts store. A properly functioning CCC carb will run very well, get good mileage, and provide lots of performance. Good luck.

Also, best to post a new question rather than "highjacking" an existing post.
Posted By: jwat

Re: Take out Computer or Fix it? - 09/08/10 07:09 PM

87ChooChoo, First and foremost, I apologize for "highjacking" the post. The only plug disconnected from the carb is the driver's side plug. I'm not sure whether that goes to the mcs or the tps. When I turn my key on, I hear clicking without the plug in. So, does that mean the tps is bad? I havent taken a meter home yet to read out the plug. Is the tps IN the carb? I am not too savvy with computer controlled carbs. I know a little about either carburated or fuel injected, not the combination. From what I know, the tps is something external to the carb/throttle body. If it is the tps, can I just replace that without rebuilding the carb? Thanks for your help so far.
Posted By: 87ChooChoo

Re: Take out Computer or Fix it? - 09/08/10 07:23 PM

TPS is in the carb, on the drivers side front. IIRC it is a three wire connector. There is also a small solenoid external to the carb on the drivers side, with one wire going to it, that increases the idle speed when the AC is on.
The clilcking is the MCS solenoid (Passenger Side Connector)- that is good to hear that it is clicking- means it is probably OK. If your TPS is out of wack, and connecting it causes problems, then it will send the wrong signal to the ECM. Need to check it with a Volt Meter. Leaving it unconnected is probably triggering a full rich condition on the carb. Plugging it in, if it is badly out of adjustment, is just confusing the ECM.

Carb will need a slight rebuild to replace it if it is bad- gaskets and a new TPS. Not a hard job, but some mechanical skills are required and some specialty tools ( Torx Drivers, TPS Adjust tool). Only problem is that once you replace the TPS, you may find other problems with the same carb ( bad float, leaking plugs are common). If you are going to the trouble to fix the TPS, and have to pay someone to fix it, I would consider going with a rebuilt CCC carb ( About $300), unless you are good at mechanical things. Then I would recommend getting the tools and learning the carb. Over the long term, you will be glad to have that knowledge and experinece.
Posted By: jwat

Re: Take out Computer or Fix it? - 09/09/10 10:30 PM

Well I am somewhat mechanically inclined, but if a rebuilt carb will fix the problem, then I would much rather do that than take out the computer and start that project. I wish this wasn't my daily driver but unfortunately I got put into the situation unintentionally. Anyway, thanks for your help. Hopefully, my next post on here will be about something to start the restoration/upgrading rather than trying to fix it just to drive it!
Posted By: 06mcss

Re: Take out Computer or Fix it? - 10/07/10 05:36 PM

I have done the black w/white wire cut on the green buffer box, and grounded it to the ground of the radio wire harness. but I still have no cruise control, I tried to check for a c/c fuse but couldn't find any. is there a certain ground black wire in the radio harness that the c/c ground wire has to be grounded to?..tia...Bill
Posted By: 06mcss

Re: Take out Computer or Fix it? - 10/10/10 03:50 PM

any help from anyone?
Posted By: 86 ls montecarlo

Re: STICKY: Cruise without the ECM.. The Answers !!!! - 09/07/12 06:33 PM

hi my name is Tom and i have an 86 ls with a small block 400 in it i have been battling with getting the crurise control woking ive been throw everything changed the brain module a few times i also cut the ground wire from the computer and grounded it to the body and it worked great for one day and then has not worked since i would really love to talk to you. my number is 561-706-3633 could you plz call thx so much
Posted By: mmc427ss

Re: STICKY: Cruise without the ECM.. The Answers !!!! - 09/09/14 02:32 AM

Cruise is stand alone, meaning it doesn't need the ECM to work. But it done need the VSS sensor, located behind speedo, and the VSS Speed Buffer, the little green module under the dash. Module is 6 wires, three (BLK, RED, GREEN) run to the sensor on the speedo, PNK/BLK is IGN 12+ power, YELLOW runs (inputs)to the Cruise module, BRN runs (inputs) to the ECM. This BRN wire you don't need if you don't have an ECM.

Usually cruise problems are caused by a bad or miss-adjusted brakelight/cruise switch at the brake pedal. The vac valve in that switch releases the vac when the brake is applied. Also the brake light switch has two sets of contacts, one set opens/closes the cruise power supply, the other set of contacts in the switch of course work the brake light. Or the staulk on the steering column has a bad switch, or the very, very fine wire of the staulk harness that passes down through the column breaks and goes intermittent. Over the years have had all of the above problems with GM cruise. Never had to replace a cruise module or cruise servo yet.

Make sure you have a vacuum ball (reservoir) and a check valve install at the source to maintain vac in the cruise system. And of course no vac leaks in the cruise system.
Bob
Posted By: wanadrv

Re: STICKY: Cruise without the ECM.. The Answers !!!! - 09/22/14 03:20 AM

Sorry to ask a very stupid question, but can you define VSS? Also, I am putting a dash back together and have no place to "hook" that wire up in the back of the instrument cluster. The pink/ black wire I have coming out of my fuse block that is in the position marked cruise control by the schematic has no place to plug in. Any help?
Posted By: Ole Blue

Re: STICKY: Cruise without the ECM.. The Answers !!!! - 09/22/14 05:12 PM

Originally Posted By: wanadrv
Sorry to ask a very stupid question, but can you define VSS? Also, I am putting a dash back together and have no place to "hook" that wire up in the back of the instrument cluster. The pink/ black wire I have coming out of my fuse block that is in the position marked cruise control by the schematic has no place to plug in. Any help?
The VSS stands for 'Vehicle Speed Sensor'. There is a small rectangle opening in the back of the speedometer that one end of the VSS plugs into and then a small screw holds it in place.

There are wires connected to this small rectangular looking piece(which connects to the rear of the speedometer) that connect to a light green module as described in the post prior to yours.

Hope this makes sense and helps. If not, let us know what doesn't.
Posted By: wanadrv

Re: STICKY: Cruise without the ECM.. The Answers !!!! - 09/22/14 05:54 PM

And this is in addition to the speedo cable itself? It does help, thanks!

Originally Posted By: Ole Blue
Originally Posted By: wanadrv
Sorry to ask a very stupid question, but can you define VSS? Also, I am putting a dash back together and have no place to "hook" that wire up in the back of the instrument cluster. The pink/ black wire I have coming out of my fuse block that is in the position marked cruise control by the schematic has no place to plug in. Any help?
The VSS stands for 'Vehicle Speed Sensor'. There is a small rectangle opening in the back of the speedometer that one end of the VSS plugs into and then a small screw holds it in place.

There are wires connected to this small rectangular looking piece(which connects to the rear of the speedometer) that connect to a light green module as described in the post prior to yours.

Hope this makes sense and helps. If not, let us know what doesn't.
Posted By: ls1_monte

Re: STICKY: Cruise without the ECM.. The Answers !!!! - 10/23/14 02:30 AM

Has anyone integrated the ls1 cruise box and the stock monte's cruise system to get a hybrid version that works??

In my case I have the stock speedo working via a modded tailshaft housing on the T56 with the stock speedo cable. Is it just a matter of wiring the "LS1's" cruise module??
Posted By: danielmurillo36

Re: STICKY: Cruise without the ECM.. The Answers !!!! - 12/07/15 04:10 PM

nice, thanks
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