sixbanger

I did the cluster swap. I used a gauge cluster from an 85 into my 87. (The 87 idiot light cluster is CABLE driven). Unfortunately I didn't mark out the original wiring positions on the bottom connector. The problems I'm having now are: Speedo is running too fast, my oil pressure and temp gauge don't move (they are currently pointing at 3 o'clock. I copied the wiring from the donor car and after the swap was completed I ended up with 2 extra wires. One is a tan/black stripe wire (2 of them in one connector) and a solid brown. I dont think I need the two tan ones (my car is auto). Any ideas? (After further tracking it seems my car has two brown wires in the top connector, one for speedo VSS sensor and one for battery light; would speedo still work with battery wire in it?)

oldschool

The instrument panel harness for the 85' is different than the 87'.
You need to move the pin terminals in the two connectors, (black and clear) and recreate the 1985 gauges instrument panel harness. Click on KED's thread about swaping the gauges for the lights. There's a link to another thread that has the pin positions in the IP harness connectors for the 1985 gauges dash harness. Also, you need to change out oil/temp switches in the engine and installl senders.

sixbanger

Ok now what exactly are the oil/temp senders? These senders are different between an 87 and an 85? Where on the motor are they located? I looked at ked's diagram but unfortunatley he doesn't show his finished wiring on the connector/plugs. When comparing my stock 87 wiring to the setup of the 85 unit, I think my stock setup had an extra three wires. Any idea on the speedo problem?

oldschool

The warning light cluster has switches that screw into the engine. They turn the light on in the warning light cluster when a certain condition is reached, such as, over heating! I think the factory temp switch turns the light on when the coolant temp is 258%. The gauge clusters use sender units which provide a continuous electrical value which is then translated by the gauge.
On the 2.8 the oil pressure switch/sender screws into the side of the oil filter spin on pad. There are two switches there, remove only the one that has one wire attached to it. The other with two wires is a backup switch for the fuel pump. The temp switch is screwed into the left cylinder head just behind the AC compressor. Change them both only when the engine is cold. The GM part number for the temp sender is 20536649. GM has discontinued the 80 psi oil pressure sender, however they are quite available. Go to NAPA, JK, Pep boys, etc. and ask for a Standard PS155. That is the correct 80 psi oil pressure sender for the MPI 2.8 V6.
Recheck keds post about the gauges, projek: 85 300 provided a link showing the pinouts on the connectors for the 85'gauges dash.
As for the speedo, I'm not sure. They may be geared differently. Since the warning light speedo from your 87' and the 85' gauges speedo both are 85 MPH units, why not transfer your old speedo into the new cluster. The speedo gearing would probably be correct then. Its an easy switch, just a few screws if your carefull.

Project: 85 2.8 bird

Here ya go

also wondering if anyone has a schematic to the 88 V6 cluster gauge. Would be nice to make sure the tach is hooked up right

sixbanger

Anyone know if the wiring harnesses for the oil pressure and water temp need to be changed when changing the sensors to work with a gauge cluster setup? (Going from idiot lights to gauges)

Project: 85 2.8 bird

oil pressure is definately a differnt sender. pretty sure the water temp is also, but could be wrong. try calling up parts store/web site & compare.

sixbanger

I know they are different sensors but is the wiring that plugs onto these gauge sensors different from the wiring that plugs onto the stock idiot light sensors?

oldschool

The wiring connectors on the engine harness for the senders are the same ones used for the switches. Just install the senders and attach the wiring. The temp. sender should come with its own pigtail connector.

KED85

IN my thread, I showed pics of the plugs. What is in my 1985 ride & what I scored from a wrecked 1985 car in the yard.
I'll bet your year vehicle is different, too.
What ya really need is the 1987 wiring diagram sets up of idiot light & gauge package.
THEN compare to the 1985 wiring diagrams.
I have yet to insert my gauge package.
Too many other I'm behind projects now catching up.
But very soon my gauge set up will be used.
In my wiring harness change over, I need relocate almost every current idiot light wire. And eventually add one WHITE wire for tach signal feed to gauge. I have already switched the sensors, when I swapped engines (2.8 went to scrap yard & inserted the 3.4). Yes same sensor wire connections no problems in that detail.
PS Check the tach readings is simple. Go to almost any repair garage and they should have an off car scope for which to check your in car tach for accurate reading.
I hope this provides a clue.
Oil pressure for a V6 reads to 80 lbs, not 60 as in V8.