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91 5.0 EFI Eddie Bauer
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Discussion Starter · #1 ·
I finally got my 91, FSB home and started working on it. It did not have a 4x4 hi/low button in the dash or the OD button. Just the connectors hanging under the dash. (which is barely hanging on). I installed a new used 4x4 button onto the connector and when pushed the 4X4 button, I can hear the relays clicking on the passenger side kick panel, but the front wheels did not engage.
So, on to testing.
When I push the button, I hear clicking but nothing lights up. I don't know what is supposed to light up, but everything I have read says something should light up.
I tried to turn the front drive shaft to test the "auto locking" hubs but I could not turn the drive shaft in either direction. So, I assume the hubs are locked in, but are stuck because I can't turn the driveshaft either way by hand.
If the hubs are stuck, how do I disengage the hubs?
So, on to the transfer case. Is there a way to test the transfer motor, or can I engage by hand?
Or, am I not testing correctly?
Don't know where to go from here.
Thanks, Tim
 

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27,271 Posts
Yo Fixit,
Will BBL,
For now;
Inspect Fuse 18.
177816



  • Electronic 4WD Indicator Lamp Inoperative
  • Electronic 4WD lamp not functioning properly.
  • Electronic 4WD lamp open or shorted.
PINPOINT TEST B: 4WD INDICATOR LAMP DIAGNOSIS
B1 ELECTRONIC 4-WHEEL DRIVE LAMP NOT FUNCTIONING PROPERLY
  • Check for voltage at the module harness connector Pin 4:
    • Key off.
    • Back-probe the module harness connector C2 at Pin 5 with module connected.
    • Set voltmeter to the 20 VDC scale.
    • Check the voltage between Pin 5 of the control module and chassis ground with the ignition switch off.
Is voltage less than 3V?
YesNo
GO to B2.REPAIR short to B+ between control module (Pin 4) and the electronic 4-wheel drive warning lamp.
B2 ELECTRONIC 4-WHEEL DRIVE LAMP NOT FUNCTIONING
  • Check for voltage at the control module Pin 5:
    • Back-probe the module harness connector C2 Pin 5 with the controller module connected.
    • Set the voltmeter to the 20 VDC scale.
    • Key to RUN.
    • Check the voltage between the electronic shift control module Pin 5 and chassis ground.
Is voltage steady and greater than 9V?
YesNo
GO to Pinpoint Test C.REPLACE control module.
PINPOINT TEST C: BRAKE SWITCH INPUT DIAGNOSIS
C1 STOPLAMP OPERATION
  • Check for stoplamp operation:
    • Apply the service brakes and observe the rear stoplamps.
Are stoplamps operating with brake pedal depressed?
YesNo
GO to C2.REPAIR the stoplamp circuit and RETEST.
C2 BAD OR INTERMITTENT BRAKE SWITCH INPUT
  • Check for intermittent open in the control module brake switch circuit:
    • Disconnect the module harness connector C2 from the module.
    • Set the voltmeter on the 20 VDC scale.
    • Check the voltage between the module harness connector C2 Pin 5 Circuit 783 (GY) and chassis ground while the brake pedal is depressed.
    • Shake module harness. Recheck for intermittent voltage.
Is voltage steady and greater than 9V?
YesNo
REPLACE control module.REPAIR break in the module to brake switch circuit.
 

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Yo,
Just remembered, to check the lamps, turn the ignition on and ground C4 and C5. The lamps should light.
 

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91 5.0 EFI Eddie Bauer
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19 Posts
Discussion Starter · #4 ·
Yo,
Just remembered, to check the lamps, turn the ignition on and ground C4 and C5. The lamps should light.
Where are the lamps? Do the buttons light up? Can I change the bulbs inside if they do?
The truck did not come with the bottom right trim for the dash. The PO gave me the pushbutton switch, and I installed it, but don't know where any lights should light up.
Thanks, tim
 

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Where are the lamps? Do the buttons light up? Can I change the bulbs inside if they do?
The truck did not come with the bottom right trim for the dash. The PO gave me the pushbutton switch, and I installed it, but don't know where any lights should light up.
Thanks, tim
Yo,
@El Kabong can help you with these parts, because I have never seen a 91 Bronco dash.
El Kabong wrote to another 91 member;
"When it's working normally, to shift between 2hi & 4hi, you don't have to be in neutral. IIrc you can be moving at speeds up to 40mph. You need to be in 4hi before shifting to 4 low. To shift from 4hi to 4low you need to be stopped & in neutral. The dash lights & lights in the buttons should light when either engages. The lights don't light if it doesn't engage, & since they don't there's probably something wrong other than bad bulbs."
 

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Registered
91 5.0 EFI Eddie Bauer
Joined
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19 Posts
Discussion Starter · #6 ·
Yo,
@El Kabong can help you with these parts, because I have never seen a 91 Bronco dash.
El Kabong wrote to another 91 member;
"When it's working normally, to shift between 2hi & 4hi, you don't have to be in neutral. IIrc you can be moving at speeds up to 40mph. You need to be in 4hi before shifting to 4 low. To shift from 4hi to 4low you need to be stopped & in neutral. The dash lights & lights in the buttons should light when either engages. The lights don't light if it doesn't engage, & since they don't there's probably something wrong other than bad bulbs."
Thanks, I will look into testing the motor and hubs at a later date. (I don't have a garage and its currently raining)
Thanks, again.
 
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