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Discussion Starter · #1 ·
Ok I have asked before and have tried all suggestions... I checked the vss and have replaced it with 4 different ones even went to stealer for one....still no luck... Here is what happens... When you start the bronco the speedo jumps all over.....this is while still in park not moving at all....this lasts anywhere from a few seconds to 5 to 10 miles down the road...the whole time it effects the shifting till it drops off to a normal speed and runs great till I shut it off and start it again then here we go again... I would really like to get this fixed.... a little annoying..
Thanks
 

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The same thing has happen to me. What im thinking is wrong the mph cluster. Im not for sure because this is my first speedo to go wrong.
 

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J,
Exactly what Year bronco are you discussing here?
This is what I've seen you post so far;
"have had this problem on my 92 bronco..."
and
"I bought this 1996 Bronco.eddie bauer from the wifes ex.. he really doesnt know about these at all... said it started shifting funny so he grabbed and yanked on the shift linkage.... I know what you are thinking and I know there is no shift liinkage...but like I said he doesnt know about this stuff... anyway turns out he yanked on teh throttle and cruise cables... My bronco is acting like it is in limp mode but the od off is not flashing on the column... I am thinking the tps is bad and when I pulled the codes it said that the peddle sensor and the secondary air injection has low volt..."

If it's all on a 96 Bronco then you've had these problems & done this so far:
... replaced the tps and the heater core... My bronco shifts like a dream now... no problems
... ign tune-up - plugs, cables, etc.
... cruise does not work all the relays and fuses check out... now I recently fixed my horn and when I tried to turn on cruise it would not engauge so I hit the off button for the cruise and the f%#&@ horn sounded... yep the off button on my steering wheel makes my horn go off...I noticed some melting int he fuse area from teh previous owner and am wondering if maybe some wires may have melted and are touching..."
... coolant gauge is not working....there are several other electrical problems but I am sure we can get to those later... anyway.. hope to get some info..."

& the seller had prev rear end work done at a shop?

Right?

So do the Code check again; Remember to have engine @ Normal Operating Temperature before doing the KOER portion
I drive it around and go theorugh reverse, etc before I start the test; make sure all accessories are off (lights, radio, HVAC fan, etc.)

post any codes found here

I know I posted the;
Pointer Waiver TSB 96-21-11 for 92-96; "...The speedometer needle may waver and/or a light surge may occur on some vehicles when speed control is used at highway speeds between 80-113 km/h (50-70 mph). This may be due to slight dents/chips in either the exciter ring or the Vehicle Speed Sensor (VSS) and air gaps between the VSS and the exciter ring..."
for you in your previous Post here.
Any chance of finding what "rear end" work Good Year did?

Next step is to check that the VSS "signal" is getting through to the PSOM

Was the VSS connector looking good?

Sensor, VSS (also called called RABS), 4WABS & PSOM, PCM Wiring Diagram & Info for 94-96 Bronco; "..vehicle speed control may be used as a good indicator. If it works normally, then the speedometer module is at least receiving a speed input signal and the wiring and sensor can be assumed to be good..."
Source: by Steve83

NOTE, Steve advises to; To bypass the 4WABS Module & feed the ABS signal directly to the PSOM, jumper LG/Bk to LG/Y, and R/Pk to O/LB

I'd do this if the 96's AMBER ABS LIGHT is LIT.
Steve also shows what Ford stated was the resistance for the VSS sensor; "Rear axle sensor should read 800-1400 Ohms across the pins, and more than 10 Ohms from the metal shell to either pin"
but my 96 Bronco PCED, Section 5A (for DTC P0500) says; resistance should be between 170 and 270 ohms; so we have a problem here.
Anyway; the Ford VSS sensors usually are VG in quality.

I'd post the entire PCED pin-point testing for you here, but I'll wait for your response to the year and all the current DTCs
 

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np pal
I forget my real name at times.

Do the scan; post the Codes.
 

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Sounds like it could be your PSOM. Try searching, Steve83 has some good info on troubleshooting this.
 

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Sounds like it could be your PSOM. Try searching, Steve83 has some good info on troubleshooting this.
yo!
look at my replies above, I gave him Steve's Links.

btw, on our 96; The 4WABS Control Module was toasted; 2 yard 4WABS Control Modules were also bad; NO RETURNS!
The PSOM was jumpin' like a toasted frog and the E4OD shifted brutally, Amber ABS light was lit.
Went thru the Ford Bronco Electrical and Vacuum Troubleshooting Manual (EVTM), Powertrain Controls and Emission Diagnosis Manual (PCED), Service Manual CD (from Steve83) to find that the Module was toasted.
 

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yo!
look at my replies above, I gave him Steve's Links.

btw, on our 96; The 4WABS Control Module was toasted; 2 yard 4WABS Control Modules were also bad; NO RETURNS!
The PSOM was jumpin' like a toasted frog and the E4OD shifted brutally, Amber ABS light was lit.
Went thru the Ford Bronco Electrical and Vacuum Troubleshooting Manual (EVTM), Powertrain Controls and Emission Diagnosis Manual (PCED), Service Manual CD (from Steve83) to find that the Module was toasted.
Oh, Im sorry bud. I wasnt trying to steal your glory. There was so much info on your post I must have over looked.
 

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NP swampfisher.

Problem now is that there are many new folks coming here now and since Steve doesn't post hardly anything anymore, the folks don't know about him and his SM site.
 

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I came across something alot like this recently. It turned out to be a bad diode in the alternator that put a rf signal into the speed sensor line. I unplugged the alternator electrical connector and it went away.
 

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Well I am a mechanic by trade and this was on a 2001 superduty that would die when it hit 1100rpm. I was doing my key on engine running selftest when the scanner could not complete it due to excessive vss. So i monitered my vss and when my target rpm was hit the pcm would have the speed limiter kick in and since there was no laod on the engine it would stall. Naturally I started unplugging stuff untill my interferance signal went away.
 

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ok thanks Mr. B!
I know that we can add mileage to PSOMs (to get yard PSOMs up to original mileages) and often heard of how those diodes can interfere w/PCMs and also PSOMs but never found anyone that actually discovered it until now, so ty again!

Also can you confirm this? I wrote this in my prev reply here;
Steve also shows what Ford stated was the resistance for the VSS sensor; "Rear axle sensor should read 800-1400 Ohms across the pins, and more than 10 Ohms from the metal shell to either pin"

but my 96 Bronco PCED, Section 5A (for DTC P0500) says; resistance should be between 170 and 270 ohms; so we have a problem here.
In an e mail discussion w/Steve he did say he copied the R values from his Ford PCED awhile ago and didn't know if Ford has made any changes to the VSS (ABS/DSS).
What does your Ford info indicate for the 95-95 VSS R values?
 

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Discussion Starter · #14 ·
Sorry guys.. I have had her in the air for a while now and still working on issues.. Got most worked out but still this bouncing speedo.. have checked tone ring and teeth and everything looks good there... I figured that as it only does it at start up and quits then runs fine that it was not in the rearend. Still chaseing electrical demons.. That is what I get for buying something from someone with no mechanical exp. All fuses were too big (30 in the place of a 15) as well it looks as if there was a small fire in fuse box under dash. I appreciate all of your suggestions and am working on trying on all. My abs light is on and when speedo is bouncing the abs light flickers. Once speedo drops to normal it shifts fine and doesnt do it again till I start the Bronco again. wierd. Anyway I will keep you posted...sorry for the late responses but it is busy time at work and hard to float all things...
 

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NP pal; I was in same sit when my 4WABS Module went bad and I had to do boo-koo troubleshooting.

You can do the VSS test w/diggie multimeter as sjhown in Steve83's SM site.
But the Bronco Electrical and Vacuum Troubleshooting Manual (EVTM), Powertrain Controls and Emission Diagnosis Manual (PCED), Service Manual CD (from Steve83; use adv search here for his name and then in his profile, use e mail to contact him for the CD, best under $10.00 item you'll ever buy for the Bronco) is the only thAng that can help you completely; esp for the wiring sit.
 

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Discussion Starter · #16 ·
Thanks again for all your help....need to get her going....snow is not far from flyin......
 

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Well I am a mechanic by trade and this was on a 2001 superduty that would die when it hit 1100rpm. I was doing my key on engine running selftest when the scanner could not complete it due to excessive vss. So i monitered my vss and when my target rpm was hit the pcm would have the speed limiter kick in and since there was no laod on the engine it would stall. Naturally I started unplugging stuff untill my interferance signal went away.

Do you have original DTC Mr. Bell?
 

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Due to the fact that it would not complete the koer test there were no codes produced. But I do believe that there was a p0500 in cmdtc if memory serves me well.
 

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ty!
Am checking with friends on this possibility since a few 96 owners are having DTC P0500 codes and have gone thru the entire pin-point testing in the EVTM/PCED..and found all is ok.. so we'll hav em look at the alt output next.
Thanks again Mr B!
 

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I saw this and have the wandering needle at highway speeds. The bolt hole was stripped out that holds the VSS into the housing. Can it not being tight enough cause that much air to get it? It is snapped in because the O-Ring is seated in there. I have removed the VSS a few times recently and placed it on the ground. Could that do it? Any idea on what to do to get the bolt to stay in? It looks like I can't tap it due to it not being a through hole. I also upgraded to 4.56 gears and it did it right after I swapped them in. I will go get a new sensor but prefer to not throw parts at if not needed.
 
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