PFF - Pennock's Fiero Forum, PDA Edition

2nd Gen Headlight Pin Replacement (Page 5/6)

Chris Eddy

APR 13, 05:51 PM

This may be related (or Ill give you a full refund)..
I looked at the gen 2 headlight control module circuit. I was expecting a circuit that activates for a set time period, but also measures current and shuts off when it measures a certain amount.
This is not the case.
The circuit appears to be a timer (there are 2, it is a dual circuit with one relay and two transistors) that activates for a set period of time. There does not appear to be any measurement of current at all. So that means that when the motor hits the end stop, the circuit will deliver a lot of current for the remaining time that the circuit is on.
So I put an oscilloscope on it, and verified this.
When the motor goes in the open direction, it draws about 1.6A. But it starts briefly at 5.3A and ends at 4.6A.
The total time to open is 1.75 seconds.
When the motor goes in the down direction, it draws about 0.7A. But it starts briefly at 5.3A and ends at 5.3A. When it reaches the end, it briefly steps up to 2.1A, then goes to 5.3A. Could this be the cushion pin? Go ahead and laugh, I repaired mine with small cylinders of oak dowel. So there is no play in them.
The total time to close is 1.50 seconds.
But there is no evidence of a prolonged high current state. So if it were just a simple timer, it would draw current for an additional time.

Rodney

APR 13, 08:03 PM

When I was trying to replicate the 87/88 controller I put a small light bulb on the wires to my 88 headlight motor. The light lit when the motor was running and shut of that exact time the headlight was full open and full closed. I did a short video of it. It certainly appears to be a current rise switching device. When my pins were bad years ago it would go part way up and dance for several seconds. So yes there is a timer but it also appears to be a current rise controller.

------------------
Rodney Dickman

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Chris Eddy

APR 13, 08:34 PM

I think I see it.. the power transistors have an on resistance. As the current rises, the voltage on the transistor rises. I see traces that go to a smaller transistor and then the IC. So they are sensing current on each of the motors by the loss across the transistor.
The relay determines which direction the motor polarity is. The transistor is the on switch to enable the motor.
What about those connectors.. if I could get those I could make a replica.
Meanwhile I will make a device with pigtails and connectors on it.. I have some 4 and 5 pin Metri-pack of that male type on the way to play with.

Rodney

APR 13, 08:51 PM

Good luck. The IC chip is renumbered and we had no idea what it was, did. We gave up.

theogre

APR 13, 09:33 PM

quote

Originally posted by Rodney:
Failures like this are extremely rare. I've seen a few spin on the shaft thru the years. Maybe a few dozen over many many years. I've sold thousands of kits. Firebirds and C4 Corvettes also. If spinning on the shaft was a common problem it would be discussed here on a regular basis. It is not because it rarely happens. At most a handful of people have contacted me thru the years with slipping aluminum pieces. That is Fiero, Firebird and C4 Corvettes combined. C4 Corvettes take a lot more abuse and some (not all that uncommon) actually strip the teeth out of the factory plastic gear. Yet very, very few C4 Corvette owners ever have the aluminum piece strip on the knurled shaft.

Nice spin.

Broken plastic gear or spun output shaft are both cause by Delrin pins. Metal gear w/ Delrin pins just move the fail point to the output shaft or any other part that's "weak."

Reviews are most first few days after fixing current problem. Very Few will report problems after using a product months to years latter.

More likely is not a regular topic:
Many collector and others don't drive much or at all. If they drive then Rarely at night and Never in bad weather if possible. Example: I drive my Fiero only local and mostly day time for ~10 years now. I have other cars to take a trip, drive when snow on roads, etc.
Many owners sold or junk the car before they have this problem.
When the motor dies again is often someone else's problem and never go online to report it. Many have no clue what the problem is even if they figure out the pins aren't OEM.

Then add You can get new Gen2 GM/ACdelco units until last few years and Cardone sells Rebuilt and New motors thru AZ and others so many just get them when motors go fatal and never bother why.

Then add PFF and other claiming Many Thousands users but is bs. AOL and others even counts cancel accounts to reach the number they claim. Active users are wholly different number and active member changes over time.
Forums has many users asking 1 or 2 questions then leave because only value was finding the answers. Example: MrFieroUK has 30 Posts in 2001-2. Some are needed to get pass MOT inspection but fail for brakes then came hear for help, tried a few thing, and never heard from again.
Many users have several users names for various reasons.

theogre

APR 13, 10:19 PM

quote

Originally posted by Chris Eddy:
This may be related (or Ill give you a full refund)..
I looked at the gen 2 headlight control module circuit. I was expecting a circuit that activates for a set time period, but also measures current and shuts off when it measures a certain amount.
This is not the case.
The circuit appears to be a timer (there are 2, it is a dual circuit with one relay and two transistors) that activates for a set period of time. There does not appear to be any measurement of current at all. So that means that when the motor hits the end stop, the circuit will deliver a lot of current for the remaining time that the circuit is on.
So I put an oscilloscope on it, and verified this.
When the motor goes in the open direction, it draws about 1.6A. But it starts briefly at 5.3A and ends at 4.6A.
The total time to open is 1.75 seconds.
When the motor goes in the down direction, it draws about 0.7A. But it starts briefly at 5.3A and ends at 5.3A. When it reaches the end, it briefly steps up to 2.1A, then goes to 5.3A. Could this be the cushion pin? Go ahead and laugh, I repaired mine with small cylinders of oak dowel. So there is no play in them.
The total time to close is 1.50 seconds.
But there is no evidence of a prolonged high current state. So if it were just a simple timer, it would draw current for an additional time.

Either you are testing wrong or module have problems.

Yes there are timers for both motors.
But Motor drawing too many amps will shut off. Even a binding motor can trip the module to kills power as covered in my cave.
Load monitoring can be done w/o a chip. Could be looking for a volt drop w/ stalled motor not actual amp draw. I don't have time or interest to trace the module.

Simple test with w/ parts in the car...
Back Probing the motor connection w/ a volt meter or maybe a small test light should show the module will shut off at end of travel or jams.
unloaded or unplug motor then module will stay on until 5 sec timer run out.

I even check this evening to make sure. New motors are so fast w/ hood open that my old Fluke could only update the display 1 time then module is off again. 0v to 10-11v back to 0v in ~1 second (but ~11 volts aren't very accurate w/ the slow meter.) I then put a old motor to same module connector just to watch it spin for 5 sec then shut off. Started to rain and dark so stop trying more tests.

ETA--> ~11v is good here because I tested w/ engine off.

[This message has been edited by theogre (edited 04-13-2017).]

Rodney

APR 14, 04:53 AM

[This message has been edited by Rodney (edited 04-14-2017).]

Rodney

APR 14, 04:57 AM

quote

You are wrong. Period. I've sold thousands of these Delrin bushings for over 20+ years. Where are these thousands of broken motors??

theogre

APR 14, 05:09 AM

quote

Originally posted by Chris Eddy:
I think I see it.. the power transistors have an on resistance. As the current rises, the voltage on the transistor rises. I see traces that go to a smaller transistor and then the IC. So they are sensing current on each of the motors by the loss across the transistor.
The relay determines which direction the motor polarity is. The transistor is the on switch to enable the motor.
What about those connectors.. if I could get those I could make a replica.
Meanwhile I will make a device with pigtails and connectors on it.. I have some 4 and 5 pin Metri-pack of that male type on the way to play with.

Sounds about right. I was testing/posting while you post this.

the module connectors for the harness likely are not available now. even if they where years ago likely only a dealer could get them. Not a huge demand so Dorman and others likely never bothered to stock them.
Module side was likely never make as a standalone parts.

Making a module could have same problems fixed OE units... fried module and 1 or both motors. From what you say here...
If you find all parts but upgrade the MOSFET because they don't make a exact match then the MOSFET could be way off for resistance and lie to other parts keeping the power on until timer runs out. You would need to recalculate load sense circuits for the new MOSFET.

Rodney

APR 14, 05:38 AM

quote

Originally posted by theogre:

Broken plastic gear or spun output shaft are both cause by Delrin pins. Metal gear w/ Delrin pins just move the fail point to the output shaft or any other part that's "weak."

Reviews are most first few days after fixing current problem. Very Few will report problems after using a product months to years latter.

More likely is not a regular topic:
Many collector and others don't drive much or at all. If they drive then Rarely at night and Never in bad weather if possible. Example: I drive my Fiero only local and mostly day time for ~10 years now. I have other cars to take a trip, drive when snow on roads, etc.
Many owners sold or junk the car before they have this problem.
When the motor dies again is often someone else's problem and never go online to report it. Many have no clue what the problem is even if they figure out the pins aren't OEM.
.

For those reading this topic: How many of you have had broken gears or slipping shafts in their 87/88 headlight motors?