1998 B2500 Speedometer Schematic
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6th Gear
Joined: Nov 2022
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1998 B2500 Speedometer Schematic
Good morning all,
I'm working on my little truck today because the speedometer has an intermittent issue with displaying speed. It seems like when the cabin is cold, the speedometer works. However, once the cabin gets warmed up to around room temperature the speedometer falls flat on it's face. I've verified its not the RABS sensor and I can pull up live data with the scan tool to verify the pcm is getting a speed signal.
I have not tried switching speedo heads or instrument clusters. I'll post an update if I do. My guess is that it's either in the speedo or the circuit board on the back. If anyone has an old school schematic with all the components and traces of the board labelled, it would be greatly appreciated. I have the wiring diagram for the truck but not the internal schematic for the instrument cluster.
I'm working on my little truck today because the speedometer has an intermittent issue with displaying speed. It seems like when the cabin is cold, the speedometer works. However, once the cabin gets warmed up to around room temperature the speedometer falls flat on it's face. I've verified its not the RABS sensor and I can pull up live data with the scan tool to verify the pcm is getting a speed signal.
I have not tried switching speedo heads or instrument clusters. I'll post an update if I do. My guess is that it's either in the speedo or the circuit board on the back. If anyone has an old school schematic with all the components and traces of the board labelled, it would be greatly appreciated. I have the wiring diagram for the truck but not the internal schematic for the instrument cluster.
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6th Gear
Joined: Nov 2022
Posts: 6
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Update, replacing the whole IC with a different one resulted in a working speedometer.
EDIT: The circuit board was the culprit, I had to take out all the bulbs and use a pair of needle nose pliers to get all of the metal contacts that connect to the gauges. Swapping that allowed me to use my original housing and gauges, even if the mileage now isn't completely correct, the donor IC would have been way off.
EDIT: The circuit board was the culprit, I had to take out all the bulbs and use a pair of needle nose pliers to get all of the metal contacts that connect to the gauges. Swapping that allowed me to use my original housing and gauges, even if the mileage now isn't completely correct, the donor IC would have been way off.
Last edited by xcroix; Dec 14, 2022 at 04:03 AM. Reason: new info
Mountain Pass
Joined: Mar 2020
Posts: 209
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Every few years these InstrumentClusters need a good house cleaning:
blow dust out, a little silicone spray into Speedo+OdoMeter mechanism,
all new bulbs, & all electrical contacts shined up & straightened+tightened.
blow dust out, a little silicone spray into Speedo+OdoMeter mechanism,
all new bulbs, & all electrical contacts shined up & straightened+tightened.
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mikedepalma
1987 - 1996 F150 & Larger F-Series Trucks
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Feb 18, 2016 10:54 AM
