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Discussion Starter · #1 ·
I have a 96 Bronco with a 5.8 litre engine. The ABS light came on today and it is flashing a code 17. I checked the fuses and ground, swapped the main and ABS relays with the horn relay with no luck. Here is what happens, when I start the truck, the ABS light comes on for a few seconds, then goes off. If i have my foot on the brake, within 8-10 seconds after start up, I feel a pulse in the pedal, and the ABS light comes on and stays on until I turn the key off. The light comes on regardless of my foot on the pedal, but there is definitely a pulse or "thump", followed by the ABS light coming on. Any help on this would be greatly appreciated. i don't know what else to look for.
 

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Yo T,
Welcome!
Here is the 1996 Bronco Workshop Manual, partial @ 1996 Bronco/F-Series Workshop Manual

In lieu of obsolete Ford break-out box and overlays, use the pin diagram attached along with a DVOM, IF POSSIBLE.
Symptom Chart — 4-Wheel Anti-Lock Brake @ 1996 Bronco/F-Series
Reference Voltage/Intermittent Valve Fault (Code 17)
30 amp fuse open.
Intermittent connections to battery, main relay or ground.
Main relay coil or contacts open.
Open or short to ground in Circuit 532 (O/Y).
Open or short to ground in Circuit 599 (PK/LG).
Open or short to ground in Circuit 601 (LG/PK).
Short to ground through anti-lock hydraulic control unit.
Intermittent valve failures.
High resistance valves.

GO to Pinpoint Test A
PINPOINT TEST A: REFERENCE VOLTAGE/INTERMITTENT VALVE FAULT (CODE 17)
Possible Code(s)
17 — Open circuit from battery, main relay (14N089) open or 30 amp fuse open.
Affected Circuit(s)/Electrical Component(s)

A1 WERE VALVE FAULT CODES ALSO PRESENT?
If Code(s) 22, 23, 24, 25, 26 or 27 have also been obtained along with Code 17, an intermittent valve or valve wiring fault is indicated.
Are any of the above faults present along with Code 17?
Yes GO to A9.
No GO to A2.

A2 CHECK FOR FAULT REPEATABILITY
Key off.
Observe the amber ABS warning lamp and key on.
If the amber ABS warning lamp comes on, retrieve the fault codes.
If codes were retrieved, were any new codes set?
Yes If the lamp comes on but a new code is obtained, RECORD the fault code for future reference. Code 17 concern is intermittent. GO to A9.
No If the lamp proves out normally, Code 17 concern is intermittent. GO to A9.
If the lamp comes on and no new codes are obtained, Code 17 concern is repeatable. GO to A3.

A3 CHECK FOR BATTERY VOLTAGE AT ANTI-LOCK HYDRAULIC CONTROL UNIT
Measure and record battery voltage.
Install Rotunda Breakout Box 014-00322 and Rotunda Breakout Box Adapter with Overlay 007-00103 or equivalent.
Jumper Breakout Box Pin 19 to Pin 1 OR Pin 14.
Set up DVOM to measure voltage between Breakout Box Pins 17 and Pin 1 or Pin 14.
Key on. Make and record voltage measurement and key off.
Is the measured voltage between 9.5V and 16.0V AND within 0.5V of the measured battery voltage?
Yes Proper voltage is available to the anti-lock hydraulic control unit. GO to A4.
No If voltage is not between 9.5V and 16.0V, under or over voltage condition is present. GO to A5.
If voltage is not within 0.5V of battery voltage, high resistance between the battery and main relay or along Circuit 532 (O/Y) has been detected. FIND and REPAIR wiring fault. REPEAT A2.

A4 MEASURE VALVE RESISTANCE AT ANTI-LOCK HYDRAULIC CONTROL UNIT
Disconnect the 8-pin connector from the anti-lock hydraulic control unit.
Measure resistance between the following on the COMPONENT side of the 8-pin connector:
Pin 1, Pin 4 and Pin 2 (rear axle outlet)
Pin 1, Pin 4 and Pin 3 (rear axle inlet)
Pin 1, Pin 4 and Pin 5 (front right inlet)
Pin 1, Pin 4 and Pin 6 (front left outlet)
Pin 1, Pin 4 and Pin 7 (front left inlet)
Pin 1, Pin 4 and Pin 8 (front right outlet)
NOTE: Refer to the systemschematic for anti-lock hydraulic control unit pin designations.
All inlet valves should be 5-8 ohms.
All outlet valves should be 3-6 ohms.
Were all measurements within the appropriate specification and steady?
Yes
Anti-lock hydraulic control unit valve resistances check OK. REPLACE anti-lock brake electronic control module. GO to A12.
No High or low valve resistance detected. REPLACE anti-lock hydraulic control unit. GO to A12 to VERIFY concern is resolved.
A5 DETERMINE VOLTAGE FAULT TYPE
If the battery voltage measured in A3 is greater than 16V or less than 9.5V, this condition must be corrected and is the cause of Code 17. Refer to Battery and Charging System, Service to address the vehicle charging system concern.
If the battery voltage is OK, Code 17 has been generated by a low voltage condition.
Check ABS system fuse.
Is the fuse seated and intact?
Yes GO to A6.
No A shorted condition along Circuit 537 (T/Y) or Circuit 532 (O/Y) is very likely. INSPECT these circuits for a short to ground and REPAIR as necessary. REPLACE fuse. GO to A12 to verify concern is resolved.

A6 CHECK VOLTAGE AT ANTI-LOCK HYDRAULIC CONTROL UNIT CONNECTOR
Jumper Breakout Box Pin 19 to Pin 1 or Pin 14.
Set up DVOM to measure voltage between the following in the HARNESS side of the 8-pin connector of the anti-lock hydraulic control unit:
Pin 1 and known good chassis ground.
Pin 4 and known good chassis ground.
Key on. Make and record voltage measurements and key off.
Is the measured voltage greater than 9.5V?
Yes REPAIR source of high resistance or open along Circuit 532 (O/Y) between anti-lock hydraulic control unit and anti-lock brake electronic control module.
No GO to A7.

A7 CHECK FOR SHORT BETWEEN B+ AND GROUND VIA INTERNAL VALVE BLOCK SHORT
Measure resistance between the following on the COMPONENT side of the 8-pin connector of the anti-lock hydraulic control unit:
Pin 1 and anti-lock hydraulic control unit.
Pin 4 and anti-lock hydraulic control unit.
Is the resistance measured less than 10M ohms?
Yes GO to A8.
No REPLACE anti-lock hydraulic control unit. GO to A12 to verify the concern is resolved.

A8 CHECK MAIN RELAY OPERATION
REPEAT the procedure outlined in Step A6 but pay attention to the operation of the main relay.
Does the relay operate correctly?
Yes Low voltage is due to a circuit fault in one of the following: Circuit 532 (O/Y) or Circuit 537 (T/Y). GO to A12 to VERIFY the concern is resolved.
No Main relay is not operating. VERIFY main relay coil has battery voltage and Circuit 599 (PK/LG) is intact. REPAIR as necessary. If no issue is found, REPLACE main relay. GO to A12 to verify the concern is resolved.

A9 MEASURE RESISTANCE AT ANTI-LOCK HYDRAULIC CONTROL UNIT
Disconnect the 8-pin connector from the anti-lock hydraulic control unit.
Measure resistance between the following on the COMPONENT side of the 8-pin connector:
Pin 1, Pin 4 and Pin 2 (rear axle outlet)
Pin 1, Pin 4 and Pin 3 (rear axle inlet)
Pin 1, Pin 4 and Pin 5 (front right inlet)
Pin 1, Pin 4 and Pin 6 (front left outlet)
Pin 1, Pin 4 and Pin 7 (front left inlet)
Pin 1, Pin 4 and Pin 8 (front right outlet)
NOTE: Refer to the systemschematic for anti-lock hydraulic control unit pin designations.
All inlet valves should be 5-8 ohms.
All outlet valves should be 3-6 ohms. A drive over rough road is recommended while the resistance is being monitored.
Does the resistance on any valve move out of specification at any time?
Yes High or low valve resistance detected. REPLACE anti-lock hydraulic control unit. GO to A12 to verify concern is resolved.
No GO to A10.

A10 TEST FOR INTERMITTENT INTERNAL VALVE BLOCK SHORT
Measure resistance between the following on the COMPONENT side of the 8-pin connector of the anti-lock hydraulic control unit:
Pin 1 and anti-lock hydraulic control unit.
Pin 4 and anti-lock hydraulic control unit.
A drive over rough road is recommended while the resistance is being monitored.
Is the resistance measured less than 10M ohms at any time?
Yes REPLACE anti-lock hydraulic control unit. GO to A12 to verify the concern is resolved.
No Valve block is most likely OK. GO to A11.

A11 CHECK FOR INTERMITTENT LOSS OF BATTERY VOLTAGE AT ANTI-LOCK HYDRAULIC CONTROL UNIT CONNECTOR
Jumper Breakout Box Pin 19 to Pin 1 or Pin 14.
Set up DVOM to measure voltage between Breakout Box Pins 17 and Pin 1 or Pin 14.
A drive over rough road is recommended while the voltage is being monitored.
Does the voltage fall below 9.5V at any time?
Yes FIND and REPAIR source of high resistance or open in one of the following: Circuit 532 (O/Y) between anti-lock hydraulic control unit and main relay Circuit 537 (T/Y) between battery and main relay. GO to A12 to verify the concern is resolved.
No REPLACE anti-lock hydraulic control unit BLEED system. GO to A12

A12 VERIFY CONCERN IS RESOLVED
Reconnect and reassemble all components.
Key off.
Clear all codes.
INTERMITTENTS ONLY — a drive over rough road and through a car wash is recommended.
REPEATABLE CONCERN ONLY — key on and perform a short drive test.
Retrieve codes.
Was original code obtained?
Yes REPEAT A1 to address the possibility of a second related concern.
No GO to pinpoint test for corresponding code. If Code 16 was obtained, GO to Pinpoint Test X
 

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Discussion Starter · #3 ·
This is awesome info, Thanks very much! I will get on it within the next day or so and report my findings. On the diagram, I do not see where it says the location of the grounds. Do you have anything that may help me in looking for a corroded or poor ground for the ABS system?
 

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Yo,
YW.
G103 (battery to engine) Lower RH front of engine


Pic by jermil01
Component Served,
4WABS Pump Motor
Battery
Data Link Connector (DLC)
Mass Air Flow (MAF) Sensor
Powertrain Control Module (PCM), 5.0L
Powertrain Control Module (PCM), 5.8L
Right Front Park/Turn Lamp
Right Front Side Marker Lamp
Right Headlamp

===
G104 @ Rear of LH fender apron near hood hinge and 4WABS Test Connector (RED) Serves Component:
Pic @ https://s754.photobucket.com/user/jimdog32526/media/Battery/G104.jpg.html
4WABS Control Module
4WABS Data Link Connector
4WABS Relay #1

Instrument Cluster
Powertrain Control Module (PCM), 5.0L
Powertrain Control Module (PCM), 5.8L
Programmable Speedometer/Odometer Module (PSOM)
Trailer Relay Box

Other Pics by jowens1126

More non 4WABD ground pics @ https://www.fullsizebronco.com/forum/7-1980-96-bronco-tech/214581-intermittent-voltage-drop-3.html


 

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Discussion Starter · #5 ·
So I am going to report my findings on this one...I performed the tests above from the shop manual and I followed the instructions to pinpoint test A4, Measure valve resistance at hydraulic control unit. Measuring resistance between pins 1 / 4, and 2 on the component side of the plug for the hydraulic control unit, the reading was 154 ohms. Readings at all other pins were within specs, all inlet valves measured 5.4 ohms, and all outlet valves measured 3.4 ohms. At this point, it is my understanding that the rear axle outlet valve is showing resistance readings not within specs, causing my ABS code 17. Am I correct to conclude that my Bronco needs an ABS hydraulic control unit?

Which leads me to my next series of questions...If yes....

1. Can anyone recommend a source for these and are they still available?
2. Are there any special instructions to installing them?
3. Do they need to be bench bled or can I just bleed starting at the right rear and work my way around the truck like I would if I were bleeding or flushing the system?
 

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Go check out my first post. I had the HCU go out, full video and write up in the thread. Bronco ABS parts are next to impossible to find so I had to find a matching explorer part. You can see everything in the YouTube video I posted.
 

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Discussion Starter · #8 ·
Thanks, I will look at this again tomorrow and watch the videos in more detail. My Bronco seems to have high resistance in one of the valves, leading me to believe that it is one of the HCU solenoids failing according to the Ford manual. All power checked good but mine is throwing a repeating code 17 with no other codes being set. I think mine would be the actual hydraulic module and not the motor as yours was, but again, I am going to look at your post a lot closer tomorrow when I have more time to get into it. By the way, It looks like you are in Michigan, I am in New Boston, MI. We are almost neighbors.
 

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Makes sense, I was getting code 17 AND code 63, which pinpoint tested out to be the actual pump motor itself. I think you are right in believing that the motor itself is good because you are getting that peddle "thump". With a dead motor, you get no thump.
 

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Discussion Starter · #10 ·
OK, it looks like I can still order the Explorer unit on EBay. It appears that the plug is just female instead of male. That would be the difference between the F3TZ-2C215-B (Bronco) and the F3TZ-2C215-A (Explorer). Who knows, maybe once I get the 2 side by side I can swap the plugs on the side of the HCU. It looks like you just replaced the motor, however, mine has an open coil on one of the valves, so I will need to swap the entire unit on mine.
 

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Don, keep us updated on how this works out for you! I really hope it solves your problem because these abs parts are getting harder and harder to find. If this doesn't work, I did talk to a company called BBA-Reman and they seemed pretty confident that they could repair my HCU for like 200$.
 

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Yo BB,
4WABS Hydraulic Control Unit (HCU) Motor; "...pulled a motor off a crown vic, the unit it self was differant but the motor was the same. Cost me 20 bucks. OH and the wire conector was differant as well but I just drafted the one from the nfg motor on to the crown and it works great. That was 4 years ago. no problems yet...its only 2 screws that hold it in. And best part is it doesn't open the system so you won't loose fluid and won't need to bleed it. Now all you need to do is go to the bone yard and find one..."
Source: by bossind (boss, Steve) at FSB


4WABS Hydraulic Control Unit (HCU) Sources "...Used price locally is $150.00; 60 day guarantee; Babaganoosh wrote; "...BBA did the rebuilds on ABS Modules for my old VW/Audi Shop. They were super inexpensive, fast, friendly, and only had one issue with them ever and it was 50% my fault anyways (keep in mind it's VW stuff anyways...". by consensus the best re man 4WABS Hydraulic Control Unit (HCU)s are from bba-reman.com; BBA quotes $200 plus shipping for repair of/my HCU; "It usually takes about 3 days from receipt to repair..."
 

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Discussion Starter · #14 ·
Update!

Update... I installed the Explorer HCU on the Bronco. I re-wired the 8 pin plug on the 93-94 Explorer HCU. I acquired the correct 8 pin plug from a junkyard (it may also be purchased from a terminal supplier or removed from the old HCU on the Bronco) as to not have any splices or corrosion issues. The 8 pin connector on the HCU for the Explorer is a female, and the Bronco connector on the HCU is male so when retro fitting the Explorer HCU to a Bronco, you will need to rewire the 8 pin plug so that it mates with the harness in the Bronco. You could just cut the plug off of the old HCU and splice to the new one, but I purchased the correct pins and crimped them to the wires as to not have any wire spices. Also, the inlet and outlet valves on the Bronco HCU are reversed from that of the Explorer, so you will need to wire them accordingly. In other words, when wiring the plug on the Explorer HCU, make sure you wire it so that the inlet and outlet valve leads are reversed. You can check this by using an ohmmeter. All inlet valves are 5-8 ohms and all outlet valves are 3-5 ohms. The plug on the Explorer HCu is wired opposite so you will need to make sure when rewiring the plug on the Explorer HCu that all inlet valves are reading 5-8 ohms and all outlet valves are reading 3-5 ohms. Once installed correctly and bled, the ABS light is off and everything is working correctly with no issues. The ABS is functioning as intended. Took the bronco down a dirt road and performed a few panic stops and everything is operating as it should. The 93-94 Explorer HCU, which is available on Ebay will work on a Bronco if the 8 pin plug is wired correctly. Make 100% sure that the 8 pin plug is correctly wired or it will not function as intended and safety issues in stopping may result!
 
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