Everything on dash seems off
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Cross-Country
Joined: Sep 2024
Posts: 78
Likes: 3
Everything on dash seems off
So I have a 1992 f350 7.3 idi and every thing on the dash seems off. The speedo is way off, it says I’m going 140 kph when I’m truly only going 100. The tach seems off to, it says I’m idling at over 1000 rpm which I know it’s not and when I’m casually driving around it says I’m pushing 3500 rpm which doesn’t seem right because it doesn’t sound like it’s screaming. The dash also just reads error where it’s supposed to read the odometer. The temperature gauge works but only moves from resting on cold to about a cm closer to hot then stops there no matter how much I drive it. And the voltage meter says it’s being overcharged but when I test the alternator it reads the correct voltage. The transmission is acting weird and I’m wondering if it’s linked to the tach and Speedo. Anyone ever have problems like this?
Logistics Pro
Joined: Jun 2017
Posts: 3,986
Likes: 515
From: Edmond, OK
What condition are you battery cables in? Split jackets, with green corrosion and white build up is BAD! 
You can also check the ground strap between the engine and the firewall. Remove all the ground connections and burnish the mounting point with sandpaper. Use a star washer when reattaching the grounds. You can even treat the connection with some Fluid Film to prevent further corrosion.
You can also check the ground strap between the engine and the firewall. Remove all the ground connections and burnish the mounting point with sandpaper. Use a star washer when reattaching the grounds. You can even treat the connection with some Fluid Film to prevent further corrosion.
i ain't rite
Joined: Mar 2005
Posts: 65,605
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From: Marlboro Mental Hospital.
E4OD trans needs both tach and speedometer signal to shift rite. if it is not shifting properly and the overdrive light is flashing, it has a stored diagnostic trouble code.
get the codes read and that will tell you where to start looking.
get the codes read and that will tell you where to start looking.
Tuned
Joined: Sep 2024
Posts: 490
Likes: 122
From: Ougadougou
If your charge voltage is steady around 14.2 then I would assume your voltage regulator is good--still might be worth double checking since a new regulator is cheap. I would start at the batteries and check all connections for corrosion or breakage. I think there are at least two grounds from engine to frame, and IIRC there are two small grounds on the frame towards the front end, one on passenger and one on driver side. And yes, if your tach and speedo are not functioning 100% your automatic trans will not function right either. I am still new to the E4OD but it seems that your electrical system has to be perfect to get proper operation and longevity from the transmission.
I wonder if there is a main connector at the firewall that has come loose or has corrosion issues?
I wonder if there is a main connector at the firewall that has come loose or has corrosion issues?
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Cross-Country
Joined: Sep 2024
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Ok thanks, I’ll make my way out there later today to do some looking, I’m just curious, how would a bad ground cause all the instruments to be off? Wouldn’t that cause them to work then stop working then start working again? I know next to nothing about electrical but I’m just curious why a bad ground would cause that.
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K9spike
1961 - 1966 F-100 & Larger F-Series Trucks
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Mar 1, 2007 08:23 PM
