Speedometer/odometer inop. ABS light

[novamodeler3]

I've trudged through the google gauntlet from VSS diagrams to Xfer case swaps to find out why my speedo and ABS light are inop.

Now, I've swapped to a 700r4 from a 4l60e. I believe that the swap is unrelated given that the VSS connectors are on the NP246 Tcase. I could very well be wrong.

What I dont understand is the 3 VSS sensors on the tcase. I get the need for 2 (2vs4WD). But the 3rd seems like an added redundancy. I've swapped connectors around as much as the harness would let me, and still no luck.

Is it possible the unplugged connectors from the old 4l60e are telling the PCM something? If so, where could I find a diagram that I could see about jumping opens?

***Also***

If the need arises, will the np246 speed sensors support an aftermarket speedometer should I build a new cluster? Or would I need a signal converter? New Sensor?

Thanks in advance for the help!

 

[SunlitComet]

the third one is used on front shaft to determine slippage for when using the auto 4wd mode.

all of the two wire vss data get processed by the pcm and is output is on a single wire to the speedo head.

the vss produce voltage pulses of proportional to vehicle speed. gets processed by pcm and it outputs a voltage pulse to speedo head. no further info i have or know on that at the moment.

---------- Post added at 03:44 PM ---------- Previous post was at 03:43 PM ----------

Where do you want to go after hearing that info?

---------- Post added at 03:46 PM ---------- Previous post was at 03:44 PM ----------

this s kind of the reason you keep the old pcm in place.

---------- Post added at 03:47 PM ---------- Previous post was at 03:46 PM ----------

Wait, what did you do just the tranny or other swap I am suddenly blanking out. Must be my medicine. keep dozing off.

 

[novamodeler3]

I did engine and trans. Carbureted 350 and 700r4.

My goal is to eliminate the pcm all together. I'm sure that could sound blasphemous..

If I knew the lead sensor that maintains the speed, I could swap it and diagnose more. But with the 2 on the tailhousing of the xfer case, I'm confused.

---------- Post added at 04:33 PM ---------- Previous post was at 04:27 PM ----------

Also, knowing the lead sensor that sends the speed signal I could use just that alone to a new gauge, bypassing the pcm altogether...

 

[SunlitComet]

THAT IS SACRILEGE. The senors on the props feed the tcase for analysis of slipping the other is used as well but also for speedo ,pcm, cruise, radio volume... you get the idea.The main vss should be n between those on the t-case I believe. Closest on to the circular part tag.

 

[novamodeler3]

THAT IS SACRILEGE. The senors on the props feed the tcase for analysis of slipping the other is used as well but also for speedo ,pcm, cruise, radio volume... you get the idea.The main vss should be n between those on the t-case I believe. Closest on to the circular part tag.

I figured Id catch flak for dating the truck 25 years.. lol.

Maybe not 'eliminate' the pcm. Just eliminate the things that are no longer required. I suppose it HAS to stay so the NP246 will function properly with all the vss signals. Thats not to say an NP241 swap isnt out of the question though!

BUT! I did remember the 'fun' my boss and I had removing the trans and xfer case from the vehicle. Lets say, it happened rather fast, and assistance from the floor jack was surrendered without our go-ahead.
Given the magnetic aspect of the sensors, its likely that i junked em with my extrication of the trans and xfer case. Got 3 on their way to the local parts store now.

If the speedo comes back, its a win. If not, I'll hafta shoot more wiring and find the open.

Part of me thinks that the pcm isnt supplying the speedo the signal to sweep the needle (Assuming the sensors are good)

On the other hand... Why would it turn on the ABS light if it were anything BUT a speed sensor?

 

[SunlitComet]

make sure the battery hot is always on and that the ignition power to the pcm as well. the signal should pass.

 

[novamodeler3]

3 new speed sensors, still no speedometer...

Beer30 and time to hunt diagrams...

 

[tgui]

3 new speed sensors, still no speedometer...

Beer30 and time to hunt diagrams...

I know this is an old thread, but I'm having similar probs after a xfer rebuild.

Did you figure things out?

 

[SunlitComet]

details please?

 

[tgui]

Details are that I'm an idiot.

Wrong connection under xfer case vss extension. I haven't had time to test but feel its probably this.

Purple green, not purple yellow.

Also, tests can be in on pcm red connector pins 20 and 21.

Note that xfer vss resistance is about 1600 ohms.

Like this.