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Speedo not working/Hard Shifts/ABS light on/Overdrive Light flashing


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#1 sbveenker

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Posted 09 February 2011 - 08:13 PM

I have a 1995 Bronco that I just bought and the speedometer doesnt work, the abs light is on, the overdrive light flashes and as a result the transmission is shifting very hard and basically when ever it wants to. Ive read that the VSS in the rear diff sometimes goes out so I replaced that and nothing (its the same). I checked all the fuses and all of them were good. The Miles show up on the gauge but never change. Does anyone have any ideas???
1994 Bronco 351 EFI
6" Performance long Arm Tough Country Lift
35x12.5x15 BFGoodrich MTs
Custom K&N Intake
4.10 Gears
Lock-rite Locker in Front
Trac-Loc in Rear

1995 Bronco 5.8L 351
4" skyjacker lift
35x12.5x15 BFGoodrich ATs

#2 wileec

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Posted 09 February 2011 - 09:08 PM

It is related to the speed sensor VSS if you replaced the sensor maybe the wiring or maybe the teeth on the tone rine in the diff are F-ed up. All of your reported problems are from there.

Not sure why you have so many double posts? Computer glitch?
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#3 miesk5

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Posted 10 February 2011 - 05:33 AM

yo,
As Wileec advised..&
This problem could be caused by the tone ring and a # of thangs; and this reply is long, but the Ford process is EXTENSIVE... It does include checking for "terminal back-out" in each connector from VSS to PSOM and then @ EEC, plus other stuff, but the following is most likely based on other owners' experiences.

bad vehicle speed sensor (VSS) (also called ABS,, DSS sensor) sensor on da 8.8 (rear differential) or
connector/corroded wires inside connector; or cruddy/damaged tone ring in the 8.8 (Any slight dents, chips, etc., in either the exciter ring or VSS will create needle waver. Measure air gap between the VSS and exciter ring. It should be 0.38-0.51mm (0.015-0.020"). see TSB below)

bad wiring/shorts /connectors from VSS at firewall, at 4WABS Module and /or at PSOM and then onto the PCM and then to tranny

bad 4WABS Module - It is located below ws wiper fluid/coolant recovery tank. So, the connector can be corroded by leaking fluid

bad PSOM (Speedo)

My 96's same symptoms (tranny causing whip-lash, ABS light On and PSOM needle jumpin') were erratic until the 4WABS Module's microprocessors finally burnt-out. 2 yard Modules were also bad; so I jumpered the Module out as Turbo Ghost
describes below.

To bypass the 4WABS module @ it's harness's connector & feed the ABS signal directly to the PSOM,
Disconnect module (under coolant recovery /ws washer tank) & in connector
...jumper 14 (CKT 530, LG/Y) to 21 (CKT 519 (LG/BK) & 39 (CKT 491 (O/LB) to 22 (CKT 523, R/PK)...";
Source: by Turbo Ghost
http://img.photobuck...orw-jumpers.jpg

If this solves it, then the Module is probably bad or connector needs attention.

Speed Input Signal Test @ PSOM in 93-96 Bronco; "...NOTE: Only wiring harness end of connector is to be probed. * Connect Digital Volt-Ohmmeter to Pin 4 (speed in ) and Pin 5 (speed in -). * Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts as vehicle speed increases from 0 to 48 km/h (0 to 30 mph)? OR: If available, a frequency counter may be connected to Pin 4 (Speed in ) and Pin 5 (Speed in -). Does the displayed frequency of the signal increase smoothly and continuously from 0 to approximately 667 Hz at approximately 48 km/h (30 mph)? OR: * If neither a voltmeter nor frequency counter is available, 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 & tone ring can be assumed to be good.
This is tuff to do; suggest using str8 pins to back probe the connector or a back probe kit


Any slight dents, chips, etc., in either the exciter ring or VSS will create needle waver. Measure air gap between the VSS and exciter ring. It should be 0.38-0.51mm (0.015-0.020"). Check exciter ring runout per the same ring gear backface runout procedure of the appropriate model 1996 Powertrain/Drivetrain Service Manual, Section 05-00. Make sure the exciter ring is mounted correctly to the ring gear. If runout is more than 0.1mm (0.004"), perform the differential runout check per the procedure in the appropriate model 1996 Powertrain/Drivetrain Service Manual, Section 05-02A or 05-02D, to find cause and repair as needed

Tone Ring Inspection; "Take off the rear diff cover. Check the Ring Tone gear. It is located on the left hand side of the ring gear. Look to see if any of the teeth have been notched (from debris floating around in the diff.) Usually a spider gear. If the ring tone gear has been notched, it will need to be replaced to fix your speedo reading. Jack it up and rotate the tires to look for the teeth to be notched/broken/bent..."
Source: by Bighibbi

More VSS info in my site @ http://www.broncolin....php?index=139-

More 4WABS Info, Connector Location and pin out diagrams etc in my site @ http://www.broncolin...x.php?index=240

--------------
Last;
a long shot..

PSOM Inoperative, Short Circuits, Common Locations TSB 95-02-11 for 92-95 Bronco & F Series; SEE C, E4OD Harsh Shifts & D, Code 452 - see Poss. Short Locations: 1. Driver's side A pillar trim screws may have been installed thru da 17K745 Sun Visor wire assy & .. bullet connector; 3. Scuff plate screws (driver's side) may pinch the 14A504 wire assy; 4 14401 wire assy may be trapped/pinched between Half car beam & instrument panel attachment (repeated as #7. the wire harness may be pinched/shorted behind the dash where the 14401 wire assy may come in contact w/a sharp edge on dash panel wall 5. shift cable assy near tranny may chaf the wire harness; the wire harness ; 7. repeated above..brake pedal-to-dash panel wall weld
Source: by Ford via Steve83 (Steve, That dirty old truck) at http://www.supermoto...ry/media/646262

Do this Last;
ABS Light On in TSB 95-5-21 for 92-95 Bronco & F Series; "...the HO2S wires in the 12A690 (subassembly of the 14B060 battery cable) harness may become chafed and the vehicle could exhibit any one of the following conditions....Lack of proper HEGO operation may cause, or be the result of a rich or lean fuel condition, which could cause additional heat in the catalyst. Perform self test KOEO and KOER, service any codes. CHECK FOR PROPER HEGO GROUND. If the HEGO ground is good, the following areas may be at fault: ..." READ MORE Source: by Ford via ChiltonSpeedometer inoperative
Back-up lamps inoperative
Daytime running lamps inoperative
Trailer battery charge relay inoperative
MIL on, displaying Codes: 172, 173 or 41 for HO2S failure
Inadvertent PCM Self-Test
Perform self test KOEO and KOER, service any codes. : ..." READ MORE
Source: by Ford via Chilton @ http://content.chilt...2HmgR%2bA%3d%3d

================
Also get the Codes scanned for Free
or DIY using our pal, BroncoJoe's process


The engine temperature must be greater than 50°F (10°C) to pass the KOEO and greater than 180°F (82°C) to pass the KOER.

Run it around to heat the engine up and shift thru all gears incl Reverse. Then turn off all accessories/lights, etc.

Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.

Do Key On Engine Off (KOEO) portion first.
Post any Code(s) found here by KOEO & by KOER
GL!

in my archived BRONCO TECHNICAL

site; http://web.archive.o...s.com/index.php?;
select a LINK, Right Click and and Hit Properties;

copy the the second HTTP address

paste in a new browser to see the current page

96 Bronco, E4OD, Man Xfer Case & Hubs
Thanks to All Who Serve


#4 Broncos4BAJA

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Posted 21 August 2011 - 03:27 PM

I have the same problem on my 95. I have removed the abs system completely, all the smog equimpent, and re-geared it. I have replaced the Vss, still nothing. Did you ever figure yours out?

#5 miesk5

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Posted 22 August 2011 - 02:43 AM

yo Broncos4BAJA,
Did you:
bypass the 4WABS module @ it's harness's connector & feed the ABS signal directly to the PSOM,
Disconnect module (under coolant recovery /ws washer tank) & in connector
...jumper 14 (CKT 530, LG/Y) to 21 (CKT 519 (LG/BK) & 39 (CKT 491 (O/LB) to 22 (CKT 523, R/PK)...";
Source: by Turbo Ghost @
http://img.photobuck...orw-jumpers.jpg


And Self Test?

in my archived BRONCO TECHNICAL

site; http://web.archive.o...s.com/index.php?;
select a LINK, Right Click and and Hit Properties;

copy the the second HTTP address

paste in a new browser to see the current page

96 Bronco, E4OD, Man Xfer Case & Hubs
Thanks to All Who Serve




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