Yo 93,
The gauges don't travel through nor are controlled by the computer.
The sender's should work on the 408. On the 408 ensure all ground straps etc are attached to block.
Some of the wiring diagrams:
Pin Number
Circuit
Circuit Function
1
904 (LG/R)
Charge Indicator Lamp
2
932 (GY/W)
High Beam Indicator Input
3
57 (BK)
Ground
4
450 (DG/LG)
Fasten Belt Indicator Input
5
29 (Y/W)
Fuel Level Input (with Tachometer)
6
19 (LB/R)
Instrument Cluster Illumination Input
7
57 (BK)
Ground
8
2 (W/LB)
Right Turn Input
9
648 (W/PK)
Tachometer Input Signal
10
398 (BK/Y)
Tachometer Ground (for 8 Cylinder)
11
784 (LB/BK)
Low Range Indicator Input
12
210 (LB)
4x4 Indicator Input
13
640 (R/Y)
Power Supply in RUN and START
14
16 (R/LG)
Charge Indicator Input
C1 instrument Cluster Connector
¤
Pin Number
Circuit
Circuit Function
1
875 (BK/LB)
Unique Ground to Gauges
2
658 (PK/LG)
"Check Engine Indicator" Input
3
603 (DG)
Anti-lock Brake Warning Indicator Input
4
977 (P/W)
Brake Warning Indicator Input
5
—
Not Used
6
29 (Y/W)
Fuel Level Input (Without Tachometer)
7
3 (LG/W)
Left Turn Input
8
31 (W/R)
Oil Pressure Input
9
875 (BK/LB)
Unique Ground to Gauges
10
39 (R/W)
Temperature Input
11
531 (DG/Y)
Brake Level Switch Input
12
608 (BK/Y)
Air Bag Indicator
13
640 (R/Y)
Power to Gauges, Hot in START or RUN
14
—
Not Used
C2 instrument Cluster Connector
¤
BRONCO
Pin Number
Circuit
Circuit Function
1
54 (LG/Y)
Battery Input
2
676 (PK/O)
Ground
3
296 (W/P)
Power (Hot in RUN)
4
491 (O/LB)
4WABS Signal Input
5
530 (LG/Y)
4WABS Signal Return
6
—
Not Used
7
679 (GY/BK)
Speed Output to Instrument Cluster, Speed Control Amplifier to Powertrain Control Module, and Compass ●Speed Control won't work
8
—
Not Used
9
567 (LB/Y)
PSOM Programming Connector
10
—
Not Used
11
—
Not Used
12
—
Not Used
BRONCO
Pin Number
Circuit
Circuit Function
1
54 (LG/Y)
Battery Input
2
676 (PK/O)
Ground
3
296 (W/P)
Power (Hot in RUN)
4
491 (O/LB)
4WABS Signal Input
5
530 (LG/Y)
4WABS Signal Return
6
—
Not Used
7
679 (GY/BK)
Speed Output to Instrument Cluster, Speed Control Amplifier to Powertrain Control Module, and Compass
8
—
Not Used
9
567 (LB/Y)
PSOM Programming Connector
10
—
Not Used
11
—
Not Used
12
—
Not Used
In 92 through 96, the rear axle mounted VSS provides a 72,900 to 86,900 pulses per mile signal via the 4WABS module to the Programmable Speedometer/Odometer Module (PSOM) aka Speedometer/Odometer; PSOM then converts this signal to 8,000 pulses per mile. The correct PSOM vehicle speed signal to the PCM is an AC square wave that rises to 5 volts positive and drops back to 3 volts negative, with a frequency of about 120 Hz at 60 mph. That signal is sent out to the Powertrain Control Module (PCM) aka Computer or Electronic Engine Control (EEC) that controls the shifting of the Electronic 4-Speed Overdrive Transmission (E4OD) if equipped, and then to:speed control amplifier, if equipped;and overhead consoles compass/outside temperature display module, if equipped. Overhead console module uses the PSOM signal to estimate the accuracy of the outside temperature sensor that uses a high-speed counter to monitor vehicle speed to determine whether engine heat is causing erroneous readings.
••
See Computer
Pin outs @ http://web.archive.org/web/20120118104425/http://www.oldfuelinjection.com/truckpinouts.html