Erratic Temp & Oil Gauge

[Project86FieroSE]

My 86 GT 2.8 V-6 Temp & Oil Gauge Are reading OK during Idle, but when I drive it they are reading all over the place. Is this due to bad sensors or is ther issues with the computer? I replaced the Amp/Oil gauge cluster over the center dash and it still is erratic, but not as bad. The Amp side stays even. The oil side reads much better than the old cluster at idle. I get readings of 60-80 during Idle, but then it randomly reads below 20, light comes on, and then pegs the guage during driving. Same with the temp guage. This is also causing the fan cooling system to not come on when the temp reaches 235. I have to press the air conditioning on to activate the cooling fans manually. Any direction as to what I need to look at would help. Thanks.

 

[glake89]

Weak connections, bad grounds.

 

[Project86FieroSE]

Thanks for the information. I started going through the electrical starting with the battery connections. WOW. The previous owner had no concept of wiring or grounding. The battery cables and associated wires are all messed up. I'm going to re do the battery cables and make a battery box that fits and will support the battery correctly. Currently they used a Ford battery tray and a bunge cord to hold it in place. Also they attemped to use top mounted posts instead of the side mounts.

 

[86FieroSE]

Check the connection behind the radio that the guages use. If it hasnt been messed with it should be clipped to the plastic frame.

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[Project86FieroSE]

Oh its been messed with. Cut wires here and there. Looks like it was done so they could remove the factory radio connection. (Guess they could not spend the $10-$15 on an adapter kit) So I got one from a donor car to try and match the cut wires. Also see if they cut other wires besides the radio connections. What a mess! I have no dash lights or door lights.