tom76

I am helping a friend install a 4L60E into an 1987 Cutlass. I am going to use a 16197427 for the transmission controller. The 4L60E can be built with the 700R4 tailshaft housing to retain the mechanical speedometer, and I could use this pass through sending unit to supply the pcm with the output speed. I have searched, but have not found anyone else that has used this. Everyone seems to run a modified tailhousing from jagsthatrun, etc. or they run a box that drives the speedometer cable. From what I see the code will need to be modified because it is 8k ppm vs. the original 4k ppm. So, has anyone tried this and is there any downside?
Thanks,
Tom

junkcltr

iTrader: (1)

The thing is that the 427 ECM controls the tranny using the 40 ppr signal and the engine using the 2K ppm signal.
The 40ppr signal is buffer using the DRAC and it also creates the 2k ppm signal.

The code will need a mod to make the trans run off the 2k ppm signal. Since it is "bad" resolution then all the tranny slip code stuff will probably need to be removed from the code.

The 40 ppr signal is the way to go, but I am also in this situation needing to only have the 2k ppm signal due to the 4x4 box behind the trans. At some point in the near future I need to make the code mods.

EDIT: The 87 Cutless has a 2k optical VSS behind the dash on the mechanical speedo, right? I thought I have pulled a few in the JYs from those types of cars. It is a yellow or green box attached to the back of the speedo. If you run the optical speedo like I do then install the 700R4 gear driven output and the speedo will provide the 2k ppm signal, but you still need a code mod.

tom76

I'm sorry I grabbed the wrong part #, should be SEN-01-4160 for the pass through style. I will be using the PCM only for transmission control. I thought the PCM needed 4k ppm and the 2k ppm was used for driving electronic speedometers.

dyeager535

2K on the "older" GM stuff ('82-ish even up to at least '91 for R/V trucks) used 2K for cruise control, even an applications without an ECM. On the A/G-bodies, trucks, etc., the optical eye was mounted to the back of the speedo.

I assume an electric speedometer isn't in the cards for the Cutlass? I've got a Cutlass too ('85) but it's been long enough that I'm not sure what is out there for them aftermarket.

I wonder if one of the truck speedometer setups ('90-91 R/V) could be retrofit to the Cutlass speedo (just the electronics, not the face, far too large)? I converted my truck over to the stock electric speedo setup (with the 40 tooth reluctor t-case setup) and the DRAC makes things pretty clean and easy, especially speedometer calibration for tire size changes.

Exchanging the speedo cable for two wires was a plus IMO as well.

I guess where I'm going with the DRAC deal is that last I looked, most of the "converter" boxes for signal generation were pricey, and added more connections to the speedo cable. Maybe that's changed.

tom76

I looked back over my notes and you're right junkcltr, it does require a 40 ppr signal. I don't know where I got 4k ppm from. I asked dakota digital how many ppr the SEN-01-4160 generates and will let you know when I get an answer. Also since this is being driven by the mechanical speedometer output the value will have to be adjusted for the drive/driven of the speedo gears installed since it is not directly reading the output shaft.
Electronic speedometer is not in the cards dyeager535. I have thought about using a DRAC or an SGI-5 from dakota digital to modify the signal, but was hoping to just hook the SEN-01-4160 straight to the PCM and then modify the code.

junkcltr

iTrader: (1)

From memory the engine code wanted a 2k ppm signal.
The trans. wants the 40 ppr signal.

Since you just want trans control you will need the 40 ppr (stock 4L60E reluctor) or do some code mods.
Since you only want this PCM for trans. control then what ECM/PCM is controlling the engine and what VSS is being used for it?

tom76

The engine is a GM Fastburn 385 with a carb and hei distributor, so no ECM/PCM on the engine. This will be a standalone transmission controller.

junkcltr

iTrader: (1)

Either way you will need a code mod to create 40 ppr.
It is easy to take a fast signal and divide it down to a slower signal. There is no worry of aliasing. Going the other way is problematic sometimes.
What you need is a device that receives the 2k ppm and generates the 40 ppr signal (as a constant duty/freq) until the next 2k ppm. So the code would see "stepped" values of the 40 ppr signal changing at a 2K ppm rate. Or go in the code and make up this signal using the 2K ppm input (or 4K ppm) input that you already have for the existing EFI engine control.
I see problems with the trans slip code (and SES light codes) with doing this. So be prepared to possibly need to disable some of this code.

junkcltr

iTrader: (1)

Exactly why I asked. I had a feeling other sensors were missing. You will need a TPS and DRP input at a minimum. I would have to look at the code to see if other sensors are required. DRP is no big deal, but does the carb have a TPS sensor installed?

tom76

I recieved a reply from dakota digital and the sensor is 4 ppr. Which after going through the speedo gears will be 1.36 ppr, which I don't think is going to work. As for the other sensors I will need: holley makes a TPS kit for the carb, I will being using a 1 bar GM map sensor, a GM coolant temp sensor, and I think there were a couple of other inputs I needed. The output speed sensor is the one that I am not sure which way to go. I really didn't want to spend big money on a custom tailhousing or a box to drive the cable if it wasn't necessary.

junkcltr

iTrader: (1)

I know with my setup I can either swap to a different transfer case which was only available in one vehicle for 1-2 years or change the code. My choice right now is to change the code. In your case do a 40/1.36 multiply to the counts coming in and round. Of course, resolution is lost and that is why I think the trans slip code will have a fit about it.

EDIT: If you are going to modify the code then I would just set the Coolant temp value in the code and not even install the sensor. Maybe do that with the MAP sensor and other unnecessary sensors for E-trans. The constants would be to keep the engine code happy.

junkcltr

iTrader: (1)

Some rambling here:

Stock speedo wants to see: 1K pulse/mile
optical VSS is 2 ppr, so 2*1K = 2K pulse/mile
Dakota 4 ppr, 4*1K = 4K pulse/mile

Yes, 1.36 ppr at your Dakota sensor is correct.
Do the 40/1.36 = 29.41176 multiply to the incoming VSS signal for the E-trans code. Which really ends up using FDIV to do this sort of multiply to get accuracy. But does it really matter in this case? I don't think so unless you try to keep the slip code under static cruise conditions when the VSS is high enough.

EDIT: What year 4L60E is being installed?

dyeager535

I'm sure this is not helping matters, but any possibility of just converting to TBI?

Not sure what the cost would look like comparatively, or if it would meet the goals of the engine, but it sounds like cost and effort-wise, you'll be 90% of the way to TBI just to get the 4L60E to work without a PCM controlling everything.

Of course, that still doesn't address the speedometer cable/40 tooth reluctor issue, which is additional cost.

Without going to an electric speedometer though, I don't see how you will get around the issue, short of the path you have found, a signal generator off of the speedo cable.

junkcltr

iTrader: (1)

Why not put a HEI in it that the PCM can control? I think it would be a major improvement if you are going to install all of the sensors and you need an HEI that spits out the DRP anyway.

tom76

The resolution is what has me concerned. I will have to do some more digging through the code and see how much anti-abuse is in there. I didn't think that the 4L60E had much in the way of anti-abuse code due to the lack of an input speed sensor (with the exception of the late models, '06 and up I think, that recieved the ISS). As for the year of the trans, I am not sure what year transmission he plans to build. If it were my vehicle I would switch over to TBI, but he wants to keep the carb. Besides the TBI conversion wouldn't solve the problem of the mechanical speedo and the signal required for the PCM. I know that it is easily solved by using a conversion tailhousing or a box to drive the cable, I was just looking for a more cost effective way.

dyeager535

OK another thought. Would it be possible to add the VSS reluctor ring to the trans output shaft?

I've seen similar done on output shaft housings (adding either speedo cable drive, or vss), and the reluctor ring interchanged with the speedo drive gear on some setups, it would seem maybe that would be an option, provided you could fit both the speedo drive and reluctor ring on the output housing.

junkcltr

iTrader: (1)

For a stock or mild 350 I would use the TBI over the carb. For that engine I would use the carb over the TBI.

I agree on the cost effective way. I am doing the same thing. The optical VSS is probably $5 in the JY. They tell me to just take them when I am getting real parts there. It should already have one in the car. So it should be free.
Either way, you need to do the code mod.
There is just slip code. Really minimal stuff compared to the 1998+ E-trans & engine control.

Fast355

iTrader: (2)

I would use TBI over carb on that engine....However the OP could definately benifit from computer control of the timing.