Slow Down Light- how hot should cat be?

Does your slow down lights only flicker after 10min or after car is at operating temperature?
If so, check the thermocouple wire thats going into the cat. trace that wire upwards to see if its rubbing against the edge of the cat, this may explain why it flickers and everything seems normal meaning the CAT should not be red hot. Its an easy fix, buy some thermal tape and wrap the thermocouple wire if you see it exposed. Mine had this problem and that fixed it.

 

My came on because my catalytic converters were bad, and since I barely passed smog in California, I am going to bite the bullet and replace them.

 

One of the owners manuals states the temps at which the light comes into play. I'm not home so I don't have the actual numbers. I've heard when it gets hot enough to trip the sensor the cat is glowing. Also the operation is two stage. At first it blinks at a steady rate, then when it hits the second threshold it goes on solid. If yours was more of a flicker that will be an electrical fault in the system.

 

My first Mondial had the same flicker problem and I agree with others here regarding an electrical issue.

On mine, the thermal-couple actually wore a hole through the stainless steel heat shield. This problem was pre-internet so finding a non-yellow box replacement was near impossible.
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For future searching purposes:

In the owners manual for my 1987 3.2 Mondial.

If warning light flashes cat temp is 1652 +or- 36 degrees F. 900 +- 20 C.

If warning light is steady temp is 1724 +-36 degrees F or 940 +-20 C.

That's toasty.

 

I was getting a flickering, then the Slow down light stayed on last summer. I pin pointed it to my thermocouple wire that goes into the catalytic converter. To check this, do the following:

1) Jack up the rear
2) Unscrew and remove the net grill protecting the cat/muffler
3) Identify the thermocouple wire unit on the cat, I do not think the problem is related to the O2 sensor
4) Examine the thermocouple unit, unscrew it and clean it (looks like a probe sensor thermometer)
5) Trace that wire upwards into the engine bay, it connects to the ecu, looking for snags along the way
6) On mine, the sharp metal edge of the cat itself was rubbing & eating into the thermocouple wire insulation, therefore causing a false flicker when the cat got hot and sometimes it just stayed on.
7) I got some thermo tape and wrapped the compromised area of the wire (go 4 rounds with the tape)
8) No Slow down light since I fixed it.

It does sound like you have a similar issue, so try these steps first and see if it helps you.
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That's great, mine rubbed right into the wire, it was showing even. After the thermo taping, not a flicker ! You may need to test your couple or get a new one if the problem persist.

All the best.

 

Not sure why the tape is not holding for you, but mine is on and working for me for 8 months.
But before we go further, lets diagnose two different issues here:

1) When the thermo tape was on for you, did you notice the slowdown light stop flickering or go away

2) If step one passed, how are you wrapping your tape around the wire? Its best to unscrew the thermocouple out of the cat, then you can make sure the wire can be taped on tight. Here is my photo of my wire, I started from probe nut and wrapped up about a foot and a half upwards and looped 3-4 times. Don't be afraid to use up the tape, its alot cheaper than spending $500 on a new thermocouple wire. The wire itself is bendable somewhat so try to keep it from touching the cat.

hope that helps.
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You should go to the real source of the problem and purchase Scuderia Rampante's gold connector kit for the ECU and be done with it (probably would solve over 90% of these types of problems).

 

Well I did that, had the full GCK installed on mine, but I'm still having a intermittent 5/8 slow down light illumination. It's being tracked down now, hopefully it's a simple thermocouple wire but the GCK isn't a fix all in this area, A great product yes, but TC's and ECU's do go bad.

 

True that Valenzo, so you might want to give Dave a call and see what he suggests if you don't get any satisfaction on detecting the problem.

 

I'm also going to tackle this issue and am following with great interest.

 

I'm also going to tackle this issue and am following with great interest.