3800 swap Temp gauge doesn't work (Page 1/2)
FIER086 MAY 22, 12:57 PM
I got my 87 GT Series II 3800sc running and driving last week. I have Fieroflyer's (Dan) wiring harness. I am using the stock 3800 3-pin temp sensor. I did the temp gauge fix to correct the pegging issue from the factory in the gauge cluster when the old 2.8 was in it and it worked great.

Now with the 3800sc in when I turn the key to run the needle pegs all the way in the up position pointing towards the sky. After I start it the needle remains up until i smack the cluster and the needle comes down to the 100* mark. The needle never moves from this point even when the engine is warm. What is my issue. I don't understand why it is not reading with the 3800 in it.
Any ideas?

Thanks,

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'87 GT - 5spd, Project Car- 3800SC II: Full Rebuild, VS Cam, 90# Springs, 3.4 pulley, headers, 42.5# injectors...
'86 SE - 2m4, SOLD
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So now you'd better stop and rebuild all your ruins,
For peace and trust can win the day despite of all your losing

olejoedad MAY 22, 02:22 PM
How did you perform the gage fix?
phonedawgz MAY 22, 02:27 PM
His harness isn't wired for the fix. To correct his harness at C500 cut the wires running to C2 and D3. Now splice back together swapped.
FIER086 MAY 22, 02:43 PM
I performed the gauge fix at the cluster per the write up on fierosaulils .com.

So all I have to do is splice those two wires at the C500 and I should be good?
phonedawgz MAY 22, 04:54 PM
Yes - The two wires needed to be swapped at the dash and at the engine. On the engine end, the Fiero Sails article has you swapping them on the dual temp sender/temp switch. Now with the 3800 the temp switch is the PCM and the temp sender is the Dk. Green wire of the dual temp sender (gauge)/temp sensor (PCM). The easiest place to swap those wires is at C500 on a 3800 harness.

[This message has been edited by phonedawgz (edited 05-22-2016).]

olejoedad MAY 22, 06:30 PM
The easiest and least intrusive 'fix'.....
Cut the two small gage green wires coming off of the Ignition Switch.
Splice the two free cut wires together. The Bulb Test is now disconnected from the gage circuit, the gage will not peg when starting the car.
If you want the 'Bulb Test' to illuminate the HOT light, extend the light green wires that are still connected to the Ignition switch and 'T' into the wire to the HOT light....C3-13 Dark Green wire.

No need to change anything in the engine compartment.

Blasted autospell...

[This message has been edited by olejoedad (edited 05-22-2016).]

FIER086 JUN 09, 02:09 PM

quote
Originally posted by olejoedad:

The easiest and least intrusive 'fix'.....
Cut the two small gage green wires coming off of the Ignition Switch.
Splice the two free cut wires together. The Bulb Test is now disconnected from the gage circuit, the gage will not peg when starting the car.
If you want the 'Bulb Test' to illuminate the HOT light, extend the light green wires that are still connected to the Ignition switch and 'T' into the wire to the HOT light....C3-13 Dark Green wire.

No need to change anything in the engine compartment.

Blasted autospell...




Oledadjoe,

I cut the 2 light green wires going to the ignition switch under the steering column and connected them. This did nothing to change my issue. What else should I try? Should I put the wires back to how they were? I am to the point where I might just wire in another gauge and mount it somewhere inside.
phonedawgz JUN 09, 06:01 PM
That's because his fix assumes you haven't preformed the in dash fix.

Undo your previous in-dash fix and things will work.

[This message has been edited by phonedawgz (edited 06-09-2016).]

FIER086 JUN 09, 06:12 PM

quote
Originally posted by phonedawgz:

That's because his fix assumes you haven't preformed the in dash fix.

Undo your previous in-dash fix and things will work.




At the gauge cluster you mean?
phonedawgz JUN 09, 06:18 PM
Correct.