ECU problem...improved!

alan cordeiro alancordeiro at
Wed Mar 26 22:54:33 EST 2003


I have not been to Radio Shaack to often in recent days, somemory is fuzzy,
But as i recall, The lowest current 5 volt regulators will put out 100 mA,
the typical ones will put out 1 amp. I think Hall efect units will take
10-20 mA,
(Again, a guess)

If the hall sender is using all that current, IT may be the culprit,
and going from "good' to "bad" by taking a much higher current
than before once it warms up.

perhpas (hopefully) your  ECU is good, and the Hall Effect sensor
needs to be replaced. Perhaps you can borrow one from somewhere.


----- Original Message -----
From: "Barry Doolan" <bdoolan at>
To: <200q20v at>
Sent: Wednesday, March 26, 2003 9:28 AM
Subject: ECU problem...improved!

> Thank you Alan Cordeiro for the suggestion to borrow 5 volts from
> another ECU pin to send to my Hall sender as a temporary fix for my
> ECU. Although no other pins deliver 5 volts, my mechanic installed a
> radio shack voltage regulator  from another pin to the Hall sender.
> It delivers the 5 volts fine but the amperage draw to the sender must
> be higher than the voltage regulator can handle. It gets pretty hot
> but works fine so far.  It will do as a temporary fix of getting my
> car started.
> I will have to bite the bullet and purchase another ECU. OUCH! Does
> anyone out there have a source? Are there any parts cars with a good
> ecu?
> Looking to replace within the next two weeks
> Barry Doolan
> 91200gt Burlington Vermont
> My 1991 200qt 20v has been having start problems over the past 2
> weeks related to a "Check Engine"signal. Car would start after a long
> wait (in the cold of Vermont), check engine light comes on after a
> short time, and then no start until another wait of hours. When
> brought inside in a warm shop it wouldn't start at all. Codes pointed
> to the Hall sensor but the culprit is now narrowed to pin 12 on the
> ECU which brings voltage to the Hall sensor. Voltage at this pin
> should be 5 volts but it only reads 1 to 1.2 volts. My mechanic
> connected a voltmeter to the pin at a time when the voltage read 5
> volts (car had been sitting for a day) and it started right up. On
> driving the car a short distance the voltage dropped to 1.2 volts and
> the check engine light came on. When he returned the car to the shop
> it would not start again.
> So, it appears to be a malfunction of the ECU? Has anyone had
> experience fixing this problem without replacing the ECU? If I do
> need to replace, who has a spare?? Mine is the original (I believe)
> stock ECU with no upgrades.
> I am off on a trip (flying not driving)until Thursday, but I still
> would like to see some responses on the listserve for me to read on
> my return. In the meantime anyone with a part or advice to my
> mechanic can reach Doug at constant at I am hoping to get
> this problem resolved. With  the maple sugar now running in Vermont
> the warm days will doom any more drives in my car until this is fixed!
> Barry Doolan
> Cambridge, Vermont
> Black 1991 200qt2Ov
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