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Discussion Starter #1
For the add. My desire to buy a new truck but not wanting to donate $71,000 to a dealership steered me towards fixing up the 94 Bronco. Looking to this group for good tech advice and upgrades. So far I installed a 4" Superlift Super Runner kit, new 33" MT tires and wheels, leather interior, new carpet. Just received a Jet chip upgrade and Gibson cat-back exhaust in hopes of gaining some of the lost performance from the tire size change. Also got a new instrument cluster overlay from Black Cat Customs to upgrade the look of the dash.

Premium Member
4,042 Posts
Welcome. eBay has new leather OE covers as you may know. There is the 4 bolt steering box upgrade and Saginaw powersteering upgrade. Manual hubs. Sixlitre tune-up. There's a sticky thread somewhere with alot of good upgrades.

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Premium Member
3,271 Posts

With those tires I do believe you should be able to reprogram the PSOM. I honestly don't know about the chip but I'd be skeptical.

Now let's see some pics already!

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23,348 Posts
Yo rivan_4380,
Welcome to our I'dratherkeepmyBigBroncoontheRoadthanSpendaFortuneona NewXXX....⚠

As dash_cam advised;

HOW TO RECALIBRATE THE SPEEDOMETER aka, Programmable Speedometer Odometer Module (PSOM) in 92-96 FORD F-SERIES AND BRONCO by Benjamin Ratterree

1. Check whether the conversion constant in the speedometer is correct with the following procedure:
Press and hold the RESET button on the front of the speedometer while turning the key to RUN.
Release the RESET button. The pointer will prove out and some codes will appear on the odometer display. If an "E" is on the left side of the display, the module is programmed for English display mode and should have English graphics (mph). A lower case "o" signifies an overseas (metric) graphics (kph). Verify the graphics and display modes agree. (The number appearing after the type is the microprocessor revision level and is not used in this test.)
Rress and release the RESET button again. The conversion constant and the word CAL will be shown on the odometer display.
Check the conversion constant shown on the odometer display with the chart below and verify the correct constant is entered.
Turn off the key to exit this test.
2. Reprogram speed conversion constant using the following procedure:

Locate the dealer mode programming enable single-terminal connector. The connector is located at the bottom of the instrument panel below the center of the glove box. On all vehicles, the dealer mode enable wire is Circuit #567 (LB/Y).
Insert metal clip in service wire panel connector. Clip other end to vehicle ground while the key is in the OFF position.
Turn key to RUN (not crank) position while holding down the trip odometer RESET button on speedometer. Release RESET button.
Speedometer will prove out (sweep across dial and back). The English/Metric and revision levels will be displayed. The last number of the display is the dealer mode programming lockout count. This count shows the number of allowable conversion constant changes remaining. When the count is zero (0), no additional changes can be made to this instrument cluster. If a conversion constant change is required, a service instrument cluster must be ordered. Refer to this section for ordering information.
Press and release RESET button again and PSOM conversion constant (without the decimal point) followed by the word CAL.
Press and release the odometer SELECT button as many times as necessary to change conversion constant to the correct value.

NOTE: Pressing and releasing the RESET button to lock in the new Conversion Constant reduces the number of times the PSOM can be reprogrammed by one count. The module can only be reprogrammed six times. If you change your mind and want to go back to the old conversion constant, turn the ignition switch off before you lock in the new constant.
When the correct new value is displayed in odometer window, press and release the RESET button to lock in the new conversion constant.
Turn the key off and remove the ground wire. Verify proper speedometer operation.

To find conversion constants for tires with 15 inch rims that are not listed in chart, above multiply the revolutions per mile (at 45mph) of your tire times .0135. For 16 inch rims multiply by .015. The revs/mile can be found at your tire manufacturers web site. There are slight variations in revs/mile per tire manufacturers, but using one like the popular BFG A/T (see below) will get you very close.
Example: BFG AT 33x12.50R15LT/C
Revs/mile= 636
636 rev/mile X .0135 = 8.59
8.59 would be your conversion constant

Here is a listing of popular oversize BFG All-Terrain tires with conversion constants:
Tire Size Revs/mile (at 45mph) Conversion Constant
30x9.50R15LT/C 705 9.52
31x10.50R15LT/C 677 9.14
32x11.50R15LT/C 656 8.86
33x12.50R15LT/C 636 8.59
35x12.50R15LT/C 599 8.09

Credit to Beratte for posting this and to omp.
The 92-96 Bronco & F Series Programmable Speedometer Odometer Module (PSOM) obtains information from an exciter ring next to the ring gear in the rear differential. Because the ring gear (and the excitor ring) turns at basically the same speed as the tire regardless of the rear end ratio, the speedometer only needs to be recalibrated to account for changes in tire size.

to find specs needed; go to http://www.tirerack.com
select Tire,
by size.

BF Goodrich All-Terrain T/A KO Size: 33X12.5R15
Revs Per Mile = 636
PSOM can only be re-programmed six times
PSOM Constant Calculator by Muddybronco (Eric) @ http://web.archive.org/web/20070324124950/http://www.arkansasmud.com/psomcalc.html
Locate the dealer mode programming enable single-terminal connector. The connector is located at the bottom of the instrument panel below the center of the glove box. On all vehicles, the dealer mode enable wire is Circuit #567 (LB/Y).
Here is the PSOM connector from under the dash, notice the flat pin in the connector, pic by jslax @ http://s74.photobucket.com/user/joestan/media/bronco/DSCN0749.jpg.html
"...First, you'll need to know the actual height of the tires, not the nominal height of 35" that's printed on the sidewall. To get that, make a mark on the edge of the tire at the ground, and mark the ground directly under the mark. Now, roll the truck far enough for the tire to have made three revolutions. When your mark on the tire is at the very bottom, near the ground, mark the ground again, and measure the distance between the two marks on the ground. Divide that distance by three, since there were three revolutions of the tire, then divide that number, (which is the circumference of your tire,) by 3.14. The answer you have is the true height of your tire. Write down that number because you'll need it for the next step. Divide 30282 by your actual height. If your true height is 34", the math goes something like this: 30282/34=891. That would be your speedometer calibration code."
by Rodney @ a defunct Ford message board.
Also, hope all 4 tires are same Brand and size (diameter) to avoid Xfer case/ and other problems due to binding when in 4x4 mode .

Tire Diameter/Circumference & Air Pressure Differences; "...You will recall that at the beginning of this section, we mentioned that we had made sure that all four tires on our truck were the same size, were worn the same amount, were inflated to the specified pressure and were subjected to reasonable loading. Avoiding driveline windup was the reason for this. Figure 18A shows that tires of even slightly different size roll different distances every revolution. Figure 18B shows that the same effect is true for tires that are the same size but inflated or loaded differently. Operating a 4 x 4 in 4WD with tires of different size or inflation will produce driveline windup, even when driving straight ahead!
If the vehicle is being driven in 4WD on dry, hard pavement, the driver will notice drag and may experience the hop, skip, bounce effect as the front or rear wheels release the windup..." in Four Wheel Drive (4X4) General Information, Operation & Troubleshooting TSB 92-1-8 for Bronco, F Series & Ranger (COMPLETE); Includes Electric Shift On The Fly (ESOF) Troubleshooting & Hub Operation
Source: by Ford
miesk5 Note, The tires must match in size to ¼” (.250).

Was speed control, if equipped, recall work completed by a dealership? Call local dealer or register and view status @ https://owner.ford.com; or @ https://vinrcl.safercar.gov/vin/ ... have VIN ready.
To confirm current status, use this guide by jowens1126 @ https://www.fullsizebronco.com/forum/23-technical-write-ups/457065-93-94-96-cruise-control-recalls-repair.html#post6530073
note that the 93 recall is different than 94-96

For any Bronco questions or to chat about it's planned modifications or build, it's better to post each seperately in Noobie Bronco Tech Questions. Flame free zone. This will get more attention and you can build up your post count to get into other sections such as Bronco and Ford Parts/Accessories (75 posts required to view).

Please fill out your Bronco Info with year, engine size, transmission type, transfer case type (manual or electric shift), locking hub type (automatic or manual) info & major mods such as a Lift, etc. for better responses.
Click User CP
Edit Your Details,
Scroll down to Bronco Info

Forum faqs @ https://www.fullsizebronco.com/forum/21-noobie-bronco-tech-questions-flame-free-zone/165569-common-replies-faqs.html ... includes for example;

How to use search (Advanced) @ https://www.fullsizebronco.com/forum/19-suggestions-feedback-site-help/62157-how-use-search-advanced.html

Baba Looey's Favorite FSB Links (lots and lots of tech links) @ https://www.fullsizebronco.com/forum/21-noobie-bronco-tech-questions-flame-free-zone/131287-baba-looeys-favorite-fsb-links-lots-lots-tech-links.html ... includes such as, "Tailgate Window repair & troublehooting.

How to Post Pics @ https://www.fullsizebronco.com/forum/19-suggestions-feedback-site-help/6204-how-post-pictures.html

1994 Bronco Brochure, Partial; Cover & Page 3; plus pics of EDDIE BAUER model accessories.
by BigRob at 1994 Ford Bronco Bronco Accessories pictures, videos, and sounds | SuperMotors.net

Free registration for some wiring diagrams (86 through 96) and Technical Service Bulletins, (80 through 96), same as by Ford @ BBB Industries- Premium Alternators, Starters, Power Steering Products | TSB's & Wiring Diagrams

➡ Find time to participate and VOTE in our Full-Size of the Month (F.O.T.M.) & Full-Size of the Year (F.O.T.Y.) Contests @ https://www.fullsizebronco.com/forum/27-f-o-t-m-voting/
Contests will be held in JANUARY, MARCH, MAY, JULY & SEPTEMBER. Each month in-between will be used for nominating contestants to run in the following Month.
You will get ideas by those competing. Also see the prizes! They are awesome as compared to other sites' "contests"!
Then get ready for the Full-Size of the Year (F.O.T.Y.) Contest⚠

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