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Discussion Starter · #22 ·
Ok had to take some time off from car stuff but back at it now…redid all of the grounds from engine harness, black wire(AC magnetic clutch) has voltage with ignition on…7.5 fuse blows as soon as ignition is set to on position, tach does not sweep when ignition is turned on(same fuse)…
 

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Discussion Starter · #23 ·
Ok. Lets figure this out.

I'm going to list as many wires as I can that go to the 7.5A GAUGE fuse and then we can check on your car if it is right vs the engine harness.

91 SW20 USDM wiring diagram
Page 72 Cooling Fan Warning light.
Page 55 Check Engine Light
Page 56 Potentially the ELS diode
Possibly more, I ran out of time to look.
What are the pages you’re referring to for this? Do I need to pull the cluster to get to these connections? I traced only 1 wire from the kick panel fuse box for this fuse, but it went under the dashbut I couldn’t trace it very far before it was lost in the nest…
 

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Here’s what my 16 pin looks like:

What are these abbreviations?
VISC
INT
MTT
EVP1
M+
EVP2
M-
THAM
THAM is air intake temp sensor manifold
I don't know what the rest are.
Ok had to take some time off from car stuff but back at it now…redid all of the grounds from engine harness, black wire(AC magnetic clutch) has voltage with ignition on…7.5 fuse blows as soon as ignition is set to on position, tach does not sweep when ignition is turned on(same fuse)…
The tach will not sweep. This is a 30 year old car, they never did that.
You need to unplug ALL of the items I listed and determine if the fuse is blowing with them unplugged. Then plug them in one by one to find which one blows the fuse if it doesn't immediately.
What are the pages you’re referring to for this? Do I need to pull the cluster to get to these connections? I traced only 1 wire from the kick panel fuse box for this fuse, but it went under the dashbut I couldn’t trace it very far before it was lost in the nest…
I am using the electronic PDF 1993 USDM SW20 MR2 wiring diagram document.
To get to those connectors, yes you need to pull the cluster but that's not hard.
 

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Discussion Starter · #26 ·
Ok, narrowed it down to the EA3 plug in the engine bay fuse box…white wire with black stripe went to ground, if the diagram that I found is accurate; this should be water temp sender ground? This is the only connection that popped the fuse during testing…any ideas? Note: having a battery quick disconnect was a major time saver doing this by myself.
 

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Just discovered that it’s connected to 2 under the fuse box: white w/black stripe and red…?
That is not normal. The red wire is not meant to be connected to that. The heat shrink is not OEM. They never used that, it was just tape.

The coolant temp gauge does ground to the engine. Can you determine where that red wire goes?
Red is normally the Starter relay wire but I can't tell if it's just been added in.
 

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Discussion Starter · #33 ·
We’ll I disconnected it: the oil pressure light and check engine lights both came on…I traced the oil pressure sensor and tried connecting it to that and it popped the fuse and the battery light came on…?
 

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Could be this…?
It definitely could be that. If that's for the oil level light then it's not needed. And if it's blowing the fuse then definitely don't have it connected.

What do you mean continuity? You mean the wires are connected between the gauges and the kick panel around IE3 area?
 

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Discussion Starter · #36 ·
Yes. My tester is showing connections between all of those pins(and some others and the body) and the IE3, so I’m betting they have a common ground somewhere…I’m going to run a jumper wire from the IE3 to as many dash connections as I can to see which one pops the fuse.
 

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Couldn’t find a jumper connection that would blow the fuse in the cluster…checked the code as per BGB and it’s throwing a 21 which is oxygen sensor/o2 sensor heating circuit…
That code can show up if the engine is cold.
Can you unplug the sensor and see if the fuse blows?

So where are we at? Are you still getting the fuse blowing?
Have you unplugged all the items I listed and then plugged them in one by one to see what blows the fuse?
 

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Discussion Starter · #39 ·
The fuse is blowing because of the red wire that is coming out of the IE3 plug in the kick panel that was spliced into a ground wire in the EA3 plug in the engine bay fuse box…with the red wire connected(ignition turned to ON): fuse pops and the battery light comes on, wire disconnected: check engine light and red low oil pressure light come on…
Right now I know that there are 3 wires(a/c, cooling fan and now this red one) that are not connected but I haven’t had a chance to start the car yet. It started and ran with the fuse popped before, I’m going to try to start it this weekend and see what happens…side note: my radiator fans run constantly(ignition ON) and I jumpered the radiator temp sensor plug which changed nothing…
 

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Ok cool.

Shouldn't the battery light come on with the key in the ON position anyway?
The check engine light should also be on too until the engine starts. Same for the low oil pressure light. That red wire you disconnected seems to be the root cause of the issues. It is not supposed to be connected like it was. No idea what brought the previous owner to do that.
 
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