I have looked at every post regarding issues connecting and none of the fixes seem to work. Got the aldl cable from aldlcable.com. Set the 10k resistor between A and B. Downloaded TTS Datamaster. Downloaded the drivers and installed. Connected the usb cable to pc then to ALDL port. Went to recording screen set it to com 3 did the data file thing started recording and turned the key. It starts recording but loses communication every few seconds. I tried disabling the CCM the update and every other suggestion on this forum BAttery saver is off... No screen saver. But no matter what after a few seconds I get the beep and error message.

Could it be the ALDL port that is jacked up? It is connecting but just cant keep a connection going.

I also downloaded the ALDL test program and it says it is fine when it is just the USB end plugged in but when I hook it up to the ALDL port and run the test it fails.

I'm about to run my laptop over a few times and see what data I can analyze from that... What happened to plug and play lmao

 

Update

When key is in the on position it monitors and records. When I start the engine I get the lost comm issue every few seconds.

 

what year is your c4, they did not start using a ccm until 1990, according to your profile you have an 86.

 

It is an early 1986 iron heads. PROM is BUC 1724

I took it to O'Reilly to see if they could connect with their code scanner and theirs couldn't find the ecm.

 

Sounds like a noise or ground issue, if it is fine with the ignition on but not running, then has errors when car is running.

Is your laptop plugged in your house AC while you are doing this? If so, I would unplug it. Also, don't use one of those inverters to power your laptop. They can be a source of noise. Check your ALDL pin A and E connections. Make sure they are good and clean. If issue persists, maybe the electrolytic capacitors in your ECM have dried up. Can you get your hands on an oscilloscope? You could use that to look for noise on the serial line.

 

Laptop is on battery. ALDL is clean. Tomorrow I am going to clean and tighten the main ground and see if that helps. If that doesn't work I will have to hunt around for an oscilloscope.

 

If you can't find someone with an oscilloscope, you could try purchasing a .1uF and .01uF capacitors at Radio Shack. First try the .01uF across pins A&E. If that doesn't work, see if the .1uF across pins A&E make the signal clean up.

If you do get your hands on an oscilloscope, you want to set up the horizontal scale so that one complete bit takes up the entire screen. Most modern scopes have something called 'persistence'. You want to set that as high as you can (Tektronix have infinite persistence). Look for nice transitions; rounding of the corners should be okay. Ringing/oscillating at the high/low transitions will cause your problems.

 

Do not use the 10K resistor. It affects the data that the ECM sends and you don't want it.

Did you have the cable connected to COM3? If not, why did you choose COM3?

Your car does not have a CCM, so that didn't do anything useful.

 

It has been often reported that 1986 bins only support 160 baud. This is consistent with my experience when working with 1986 bins.

Try logging at 160 baud with TunerPro, or try an 87,88, or 89 bin for 8192 baud testing purposes. If its an auto...go ahead and run with it.

1986 4+3 cars are a special case:

Years ago I adapted an 88 4+3 bin for use in 86 4+3 cars. This was done by merging the 1986 first gear detection logic into an 88 bin, and correcting the shifter switch pin addressing in the bin.

A few users had success with this bin, but I've received very limited feedback, so it might still contain some bugs.

The purpose of this bin was to support 8192 baud logging and normal (for 1986) 4+3 functionality in an 86 4+3 car without re-pining anything.

If doing this again today, I would likely just re-pin the shifter switch to the 87-88 pin location at the ecm and simply run an 87 or 88 bin, and have in effect a 4+4 with no first gear detection capability.

Then just disable the 4+3 by default in the bin and activate via switch when desired. For most users, this is probably the simplest approach.

The 86 shifter switch is connected to the pin that is used for first gear switch on 87-88 cars. This is why it is necessary to repin an 86 for the 87-88 bin.

Sorry don't have the 86 and 87-88 shifter switch pin locations handy at the moment...but this is not difficult to obtain.

Updated with 86 vs 87-88 ecm pin differences for reference.

86 ecm pins:
M/T O/D Shifter switch: C8
O/D TCC Control: A7
A/T O/D switch: C7 (open in OD,N,R or P)

87-88 ecm pins:
M/T O/D Shifter switch: C7
O/D TCC Control: A7
M/T 1st gear switch: C8
A/T O/D switch: C7 (open in OD,N,R or P)

1986 4+3 cars should repin from C8 to C7 in order to use an 87-88 4+3 bin and maintain shifter switch functionality.

 

Another (potentially simpler) approach would be to hack an 86 bin to enable 8192 baud logging directly, but I have not attempted this and have little interest in doing so due to the limited user base of 1986 4+3 cars.

 

Not true. My '86 works just fine at 8192 baud. You have to send the secret code to get it to switch to 8192 baud and then it will stay there.

I have ECM pinout information for the 1227165 ECM used in '86 through '89 cars on my web site:

http://home.earthlink.net/~cliff_har...s/pinouts.html

 

I read that CCM being enabled could make it not work. I tried both with the same result.

Also I saw your website. Awesome stuff thanks for taking the time to make it.

 

So I tried it without the resistor. Did not touch the CCM. The serial usb port is com 3. IT still is losing the data connection. I checked the voltage of the serial wire Positive in the "E" negative in the the "A" ground and it was jumping anywhere between 2.5X V to 4.5X with the car running.

 

That sounds about right.

The engine does not have to be running to log data, but of course that doesn't tell you much. Does it disconnect if the engine is not running?

 

No. With the key in the on position it stays connected. But once I start the engine it starts disconnecting. I read that the ecm grounds to the main ground bolt so I took it out and cleaned all the connectors. Still the same after. The E serial port is clean and it is a tight connection so no clue whats wrong. I called TTS and they said the cable might be bad but that doesn't make sense if it works in the on position but not when running.

 

The 8192 baud logging capability for 86 is still a bit cloudy...

Using my Ostrich, I played around a bit with BUA and BUB in my car (1988).

Using Tunerpro, I can log fine with both BUA and BUB at 160 baud with 10 k resistor using an appropriate 160 baud adx file, but neither bin will connect at 8192 baud with a typical $32B 8192 baud adx file.

My normal $32B based bin connects and logs fine at 8192 baud using the same 8192 baud definition file, cable w-10k resistor etc.

I went back and forth several times with consistent results each time.

I didn't attempt to connect with datamaster, but can give this a try later. Need to charge my battery first.

While this test does not confirm that 8192 baud logging won't work with BUA or BUB, it does suggest that something may be different with the handling of the 8192 baud polling message between $32 (1986) and $32B (87-88) bins.

I'm sending the following Mode 1 request string to connect: 0x80 0x56 0x01 0x29

It should work for both $32 and $32B, but that is not the case.

I'll give BUC a try also.

More to follow....

 

Ran another quick test, this time with Data Master 32 version 4.1.0 and BUC with same car, hardware, ostrich, moates aldl cable w-10 k resistor, etc.

Same result as before, my normal $32B based bin connects and logs just fine at 8192 baud. The $32 BUC bin does not connect.

Trying to make sense of this.

Can any other users post up an 8192 baud log file from a 1986 $32 bin? If so, please explain how you are connecting and which scan software and bin you are using. Mode 1 message details would also be helpful, if available.

irishpete86, can you post a uni file or export log showing some throttle blips with key on engine off and cranking/starting, to show that you really are connected and receiving valid data?

 

My reference for the BUA firmware in my car shows this:

so that part is verified.

I get 8192 baud communication without problems but I am using Diacom, which is a unique beast (and whoever wrote it was a genius). I don't know how it figures out how to interpret the data stream. Apparently it uses the VIN to determine that.

Some ECMs output 160 baud on pin E and when a 10K resistor is applied across A & B they output 8192 baud on pin M. I don't know if this applies to any Corvettes and if it does that would be 1990 and later. The 1227165 ECM used in '86 through '89 doesn't have the hardware to make this change. In my '86 there is no pin in cavity M.

According to my FSM, applying a 10K resistor across A & B does the following:

Closed loop timers are bypassed
EST (spark) is advanced
IAC will control engine idle to 1000 RPM
On some engines canister purge solenoid will be enabled
Park/Neutral restrict functions will be disabled

My BUA code shows this:

LC024: FCB 23 ; 8 Deg added spark advance for ALDL 10K mode, CALIB = Deg * 256/90

 

This topic has some history if you dig deep enough...

Seems that Diacom+ and Moates ECM 251 were both able to log 8192 baud with 1986 bins, so the hardware + software should support 8192 baud.

From what I've gathered, the polling message in these old logging programs was somewhat dynamic and iterative until it connected successfully. Documentation is limited, so no hard data on what works.

Funny thing, I've got Diacom Plus version 2.83 on 3.5" floppy disks along with various ALDL adaptors on hand, including the 91006 gm special-tpi adaptor, but I have never used them. I don't have a compatible 386/486 computer to test with...ugh...

My conclusion is that the acceptable 8192 baud polling message for 1986 differs from what has already been posted.

Many pieces to this puzzle...

 

Irishpete: My 92 is doing the exact same thing and I have done the laptop things mentioned in your 1st post.