Re: Anyone familiar with TCI handheld controllers for auto?
 

So here's the DD circuits:

power, ground, of course, and Input, which comes from a tap / splice, on socket 29. And number 29, is one of the 2 'Output Shaft Speed' leads. You guys knew that tho', didn'tcha???

And note the crappy connections for Input and Output. IS THAT THE SOURCE OF THE SPEEDO FLUCTUATION AT IDLE?????

https://lh5.googleusercontent.com/-d...0/IMG_5032.JPG

and the tap splice for DD Input:

https://lh6.googleusercontent.com/-p...0/IMG_5033.JPG

DD Output, brown to orange

https://lh5.googleusercontent.com/-L...0/IMG_5034.JPG

and orange, splice to a yellow, near the back of the tranny:

(and $20 says that yellow, which is going into an existing harness, is the speedo feed, to the ECM???

https://lh3.googleusercontent.com/-L...0/IMG_5035.JPG

Re: Anyone familiar with TCI handheld controllers for auto?
 

There's no Sensor Ground which is NOT the same as Ground which is for Power. The VSS sensor is looking for ground.

What wretched electrical work! :mad:[-X:thumbsdo::jawdrop:

Re: Anyone familiar with TCI handheld controllers for auto?
 

Thanks for the words of encouragement there buddy! :mrgreen:

True tho', and this truth hurts!!!

So the speedo signal path, in sum:

Shaft Speedo Output, from tranny signal generator, TO controller module, INTERCEPTED by DD splice / tap, INTO DD, OUT, to OEM yellow lead.

I cannot follow this yellow lead harness, as it rises behind driver's cylinder head.

I will find VSS input at ECM, which hopefully is yellow, and do continuity to the DD output. And IIRC, '94 VSS is yellow (or purple) ?

And remember, speedo is functioning, except for fluctuation from 0 - to 30, 50, 40, and back...


So before I attempt to make better connections at the DD, the question is, why did they even put it in?

Why can I not use the TCU speedo output?

Should I try wiring in the TCU speedo output, while I have the DD disconnected?

Re: Anyone familiar with TCI handheld controllers for auto?
 

I'm willing to bet that the fluctuation is due to the fact the VSS sensor doesn't have a solid signal ground. Its probably jumping to the power ground. I had this happen once when TPS sensor was connected to my WB so I could see TPS% as part of WB O2 datalog. Worked great until one day it didn't. TPS was all over the place. Needless to say motor ran like crap. Until I removed the TPS signal from the WB and then everything worked. I was using power ground for the signal ground. Didn't like that. Needs to be separate which is why ECM has separate sensor grounds from power grounds. Each sensor needs a reference ground along w reference signal. Some sensors may share.

Re: Anyone familiar with TCI handheld controllers for auto?
 

I'm not following here Dominic...

VSS (as now wired), doesn't have a dedicated ground? Or the DD needs another ground? Or just 2 better connections? (which I'm about to do)

Do I need to trace the leads from the VSS, from the case connector???

Re: Anyone familiar with TCI handheld controllers for auto?
 

Heres a good thread from CF. Altho this is for an OBDII PCM, the idea is the same. You can see were Pin A31 and A32 are for VSS Ground and VSS Signal. The DD unit takes that signal from the trans and translates into something that our ECM will understand. The micro switch settings on the unit are for that purpose.

Here's an interesting post from this thread:

"If 85-89 used a 2k pulse per mile VSS, there must be a typo
in the 89 service manual.

It shows a block diagram lower right corner that the VSS is 4k pulses
per mile.

If he needs to correct the VSS frequency so it can be
used on the 87 Dash Cluster he can use an electronic ratio
adapter.

If the wires are connected, I would think he would get some kind of reading on the display even if the frequency was off.

Something similar to the Dakota Digital's SGI-5 may work.
The SGI-5 can convert a sine wave from 4K to 2K but the converted
output signal does not appear from their description to be a sine wave.
You would need to contact them to see if it would work."

Here's the thread.
http://forums.c**f**m.com/c4-tech-pe...gnal-help.html





http://i32.photobucket.com/albums/d4...pcm_conn_a.jpg

Re: Anyone familiar with TCI handheld controllers for auto?
 

Alright - copy on this post fully Sir.


But what's missing (or cross wired) in my wiring?

Is it as simple as getting a line to ground, at the DD, where it says 'Signal Ground'?

Re: Anyone familiar with TCI handheld controllers for auto?
 

Took a ride, and the speedo is still jumping around from 0, while stopped, even after re-connecting the previous connections. Simple spring clamp connectors, like your stereo speakers. They had a strand or 2 in the clamp.

Theirs:

https://lh5.googleusercontent.com/-T.../IMG_4994c.JPG

Mine:

https://lh6.googleusercontent.com/-Q...0/IMG_5037.JPG

Didn't really matter... At speed, it shows in perfect sync with the handheld.

And handheld still hangs at "Turn Key Off For 10 Seconds To Save Changes". Comm Error.

Speedo seemed to behave for a few minutes after startup. Closed Loop might be energizing a circuit that causes speedo interference???

Re: Anyone familiar with TCI handheld controllers for auto?
 

Maybe got a lead on the fluctuation at 0...

https://lh4.googleusercontent.com/-w....pdf-pages.jpg

Re: Anyone familiar with TCI handheld controllers for auto?
 

You said this 3 times Dominic, and I'm just now catching what you're meaning.

Signal Ground terminal, FROM DD to [a ground]. Will TRY that tomorrow - hope a little Global Warming comes in...




Looks like they went with the Yellow one there, Pete. Purple will work also? Any chance at all that the fluctuation at 0 MPH could be because they went with the Yellow instead of Purple?

And I guess that only a jumper wire is necessary for the clutch pedal Cruise kill switch?


No, but I think I might need to go to 3.23, or 2.73, with the new OD @ .67, instead of .5 of ZF 6th. Shift light shows up near 70mph...

Dave; I don't know if the speedo drive is magnetic or what (will have to wait for small claims decision for paperwork, or info from tranny maker (RPM Transmission).