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sprinkles08
sprinkles08, Chrysler/Dodge/Jeep master tech
Category: Dodge
Satisfied Customers: 21609
Experience:  ASE Master and Advanced Certified, Chrysler/Dodge/Jeep Master Certified, Trans and Hybrid Specialist
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I have a failed temperature and gas gauge on my '96 B2500

Customer Question

I have a failed temperature and gas gauge on my '96 B2500 van. Fuses are good and I have a ground onto the instrument circuit board. I think it may be a failed voltage limiter, as this would be common to both on the older dodges, but I can't find a wiring diagram to confirm this.
JA: Have you checked the vehicle's manual?
Customer: I don't have one. I have factory manuals for all my other vehicles, but not this one.
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Yes. Checked fuses, good. Checked ground to circuit board, good.Haven't checked continuity from sensors to dash yet, or sensor resistances, as I'm looking at a common failure at this point. Just trying to figure out if this has a separate voltage limiter/regulator for the gauges, or if it's inside one of the gauges.
JA: Anything else you think the mechanic should know?
Customer: Nope, not at this point..
Submitted: 3 months ago.
Category: Dodge
Customer: replied 3 months ago.
I get 27 ohms between ground and the gas gauge input, this seems reasonable for a tank with about 3 gallons in it. I get about 110 ohms between ground and the temperature gauge input, engine is cool (3 hours since last run) power input shared between gauges is full supply at 13.3 volts. When running, the temp input goes up to 13.3 voolts, and the gasinput goes to about 6.2 volts. Is this '96 supposed to regulate the sensor voltage down to 5 volts, like my older Dodges? If so, is that voltage regulator/limiter inside the gauges, or somewhere else?
Expert:  tims auto repair replied 3 months ago.

Hi, My name is ***** ***** for the delay.

I will do my best to assist you.

first, lets try something simple,,

Remove both battery cables from the battery, touch and hold both the - and the + cables together for 5 seconds, then re-install them back to the battery

let me know if this fixed the problem

Customer: replied 3 months ago.
Tim,Yes, I've had the battery out of the vehicle for months at a time on many occasions. Problem is always there when reconnected.
Expert:  tims auto repair replied 3 months ago.

touch and hold the battery cables together for 5 seconds with the battery disconnected with the ignition on..

then reinstall them back to the battery

Expert:  tims auto repair replied 3 months ago.

if this doesnt work for you,,i think the cluster itself is bad and will need to be replaced

Customer: replied 3 months ago.
OK, I've tried that, No change. Both gauges are at minimum reading, don't even wiggle when ignition turned on or off.
Customer: replied 3 months ago.
what voltage range should I be seeing on the sensor side of these gauges?
Expert:  tims auto repair replied 3 months ago.

stand by.

someone will be right with you

thanks

Expert:  sprinkles08 replied 3 months ago.

Hello and welcome to JustAnswer!

Do you still need help?

Customer: replied 3 months ago.
I'm still working on this. I still need to get a direct measurement of the resistance across the temperature gauge while it is disconnected. I'm still looking for an answer about what the power supply voltage to the temp and gas gauges should be, measured at the pins on the instrument circuit board. Right now I have 13.3 volts, and on my older Dodges, the gauges share a 5 volt regulator/voltage limiter. I have ordered a factory service manual so I'll have accurate wiring diagrams, but I won't see that for a week.
Expert:  sprinkles08 replied 3 months ago.

The first step in diagnosing the problem was to check for fault codes in the powertrain control module. Was this done?

Customer: replied 3 months ago.
No check engine light. I don't have my OBD2 reader here.
Expert:  sprinkles08 replied 3 months ago.

These problems wouldn't affect emissions so there would be no engine light. Are you able to check for codes?

Customer: replied 3 months ago.
No, I don't have my OBD2 reader here. I didn't realize that only emissions related codes would set the CEL.
Expert:  sprinkles08 replied 3 months ago.

Did the gauges both stop at exactly the same time?

Customer: replied 3 months ago.
I think so. That's why I was asking about the 5 volt regulator shared by the these gauges on older Dodges. Is this 96 the same?
Expert:  sprinkles08 replied 3 months ago.

Neither of the sensors in question receive 5v.

If you unplug the single wire coolant sensor and ground the wire does the temperature gauge go to full?

Customer: replied 3 months ago.
I will try that now. I just pulled the plug off the back of the dash circuit board and tested the resistance of the two sensors. Gas I get 90 ohms, which seems reasonable for a tank with about 3 gallons in it (I'm assumiing this is a 10-97 ohm sensor. The temp sensor gives me about 120,000 ohms, this is wrong, so I'll pull the engine cover and check the connection and do your test.
Expert:  sprinkles08 replied 3 months ago.

Don't disturb the instrument cluster or perform any testing there yet. The first thing that needs to be done is ground the coolant sensor wire and see if the gauge rises.

Customer: replied 3 months ago.
I've got gauge out already to replace bulbs. Just jumped to ground on back of cask, gauge goes to full. Removing engine cover now to test from sensor.
Customer: replied 3 months ago.
Back of dash
Expert:  sprinkles08 replied 3 months ago.

Let me know what you find.

Customer: replied 3 months ago.
Ok, single wire sensor right behind the alternator. Shorted, gauge goes to full. Sensor reads 120k ohms, so time for a new sensor. Maybe my gas is reading empty, just because it only has 3 gallons in it, I never put more than that into it. I figured I'd get some change from empty to 4 gallons.
Expert:  sprinkles08 replied 3 months ago.

The coolant sensor definitely needs to be replaced. You'll want to add more fuel before continuing on the fuel gauge issue.

Customer: replied 3 months ago.
No temp sensor in stock here in the mountains. I'll Get it tomorrow. I have to install a new gas tank grommet on the filler before I can add a full tank of gas. That will get done tonight.
Expert:  sprinkles08 replied 3 months ago.

Let me know how it goes!