More fun with Fan issues... Different car...

[LGAFF]

Been running into mutliple issues lately.. Now the fans in my 1991 do not come on even when signaling to turn them on with the Tech one, sometimes they turn on for a split second and off.... Now the odd part, if you go into service/Diagnosis mode it will turn the fans on as it sound.

Temp gauge seems to be working per the tech one.....


Cant win I am thinking this is another ECM issue

Thoughts?

[BigJohn]

Can you check just the fans; maybe they are beginning to fail.

[LGAFF]

Did that direct power to fans, and they work....... When I run the diagnostic and it does the ECM check "12" fans come on instantly and are strong.

Gauge fuse is also good

[LGAFF]

Also swapped relays not difference

[GOLDCYLON]

Also swapped relays not difference

Lee my son just went through this on his GS was the temp sensor that also read GOOD via tech-1A. We replaced the sensor and them installed the new SPAL fans. GC

[LGAFF]

Swapped ECMS in the 91 to the 90, in the 90 the Fans work when commanded by the Tech one .. odd.

1991
-fans work with direct power to the fan motor
-fans work in Tech one Diagnostic mode.... Testing ECM
*so we know relays, wiring, and fans are good
-Fans wont command on in the 1991w/th the tech 1 and wont come on at
205 degrees as they should
-TEch one command for fan test works on other cars with the same ECM

GC how does the sensor shut down the Tech One when its in a fan testing mode?

[Ccmano]

Swapped ECMS in the 91 to the 90, in the 90 the Fans work when commanded by the Tech one .. odd.

1991
-fans work with direct power to the fan motor
-fans work in Tech one Diagnostic mode.... Testing ECM
*so we know relays, wiring, and fans are good
-Fans wont command on in the 1991w/th the tech 1 and wont come on at
205 degrees as they should
-TEch one command for fan test works on other cars with the same ECM

GC how does the sensor shut down the Tech One when its in a fan testing mode?

I'm confused, the statements in BOLD above seem to be contradictory.
H
:cheers:

[GOLDCYLON]

Swapped ECMS in the 91 to the 90, in the 90 the Fans work when commanded by the Tech one .. odd.

1991
-fans work with direct power to the fan motor
-fans work in Tech one Diagnostic mode.... Testing ECM
*so we know relays, wiring, and fans are good
-Fans wont command on in the 1991w/th the tech 1 and wont come on at
205 degrees as they should
-TEch one command for fan test works on other cars with the same ECM

GC how does the sensor shut down the Tech One when its in a fan testing mode?


New clue Lee just relating what worked for me.

[LGAFF]

Hans

With the TECH 1 there are different tests:


Diagnostic Service for when you pull codes: This is when the fans come on and it flashes the SES lights and gives you the code numbers; when I am in this test mode the fans work. That tells me the relays and wiring harnesses/grounds are not the issue

Then there is a Misc Test Mode This allows the Tech one to command systems on and off. In this case I was using the fan function and it did not work in the 91...sometimes turning on and off.. in the 90 the ECM worked fine turning on and off w/command (Go to 5:25 in the video)

https://www.youtube.com/watch?v=rSrANDurszU

[DRM500RUBYZR-1]

Swapped ECMS in the 91 to the 90, in the 90 the Fans work when commanded by the Tech one .. odd.

1991
-fans work with direct power to the fan motor
-fans work in Tech one Diagnostic mode.... Testing ECM
*so we know relays, wiring, and fans are good
-Fans wont command on in the 1991w/th the tech 1 and wont come on at
205 degrees as they should
-TEch one command for fan test works on other cars with the same ECM

GC how does the sensor shut down the Tech One when its in a fan testing mode?

Maybe 90/91 are different/ but 92 up work as follows:

Fan 1 comes on at 228
Fan 2 comes on if temp gets to 240

Fan 2 turns off when temp falls to 240
Fan 1 turns off when temp fall below 228.
Both fans come on at any temp if AC is turned on.

:cheers:
Marty

[LGAFF]

Maybe 90/91 are different/ but 92 up work as follows:

Fan 1 comes on at 228
Fan 2 comes on if temp gets to 240

Fan 2 turns off when temp falls to 240
Fan 1 turns off when temp fall below 228.
Both fans come on at any temp if AC is turned on.

:cheers:
Marty

This is a Haibeck Chip fans on at 205... doesnt happen.. and the Tech one cannot turn them on in test mode...

[rkreigh]

I had similar gremlins in my old 87 turbo buick


I got tired of trouble shooting and rigged up a direct thermostat and called it a day I know that's kinda hackey for a zr-1, but it's cheap and works great and the fans and puter don't care.

[LGAFF]

This turned out to be an issue with the Prom still waiting to see what the exact issue is with it, maybe the Prom is just bad. I was able to take a 90 Eprom and put it in the car, then use the Tech 1 to turn the fans on and off, that would not work with the 91 Eprom in the car.... and the ECM works fine in other ZR-1s

[LGAFF]

So the chip tested on another 91 and worked fine:

So here is what I know so far:

-91 ECM in 91 w/91 chip; fans do not turn on when temps hit 205 and fans do not turn on when commanded by a tech one(sometimes the will kick on for 1-2 seconds and right off). Fans do turn on when the tech one runs a diagnostic mode; so if you do an ECM check and pull codes

So we know wiring, relays, and fans are good; as fans turn on for diagnostic mode. Ive also tested fans independently, and swapped in know good relays


-If you put a 90 chip in the 91 car with 91 ECM, and tell the tech one its a 90 the fans can be commanded on and off by the Tech one to turn on

-If you put the 91 ECM in a 90 ZR-1 w/90 chip the fans work when at 205 and can be commanded on by the ECM

These tests repeat consistently and same results time and time again. Ive done these checks as well as reseated the prom 10-1t times each.

Any thoughts, this is very odd... I have one wildcard this could be......

[LGAFF]

So the conclusion is that there is something wrong w/ECM that seems to impact the 91 Chips and not the 90s... very odd. Had some videos of the tech one and the different chip results in same car/ECM but they wont load

[LGAFF]

1991 Chip in 91 /w 91 ECM
https://youtu.be/SNCnaClA9go

1990 Chip in 91 with 91 ECM

https://youtu.be/SNCnaClA9go

[-=Jeff=-]

so apparently that ECM is now a 1990 ONLY?

[XfireZ51]

Lee,

Can take 1990 cal, copy it, and put in different prom or Ostrich. Then see what happens.

[Corvette95]

Does the Tech1 show fans requested (on) and they don't run? Pull the connector to the high a/c pressure switch just to see what happens.

[LGAFF]

Does the Tech1 show fans requested (on) and they don't run? Pull the connector to the high a/c pressure switch just to see what happens.

Hi, Makes no difference....

[Corvette95]

Does the tech one show fan command on? (not in field service mode) . Hook up Tech1 and turn a/c on. Does the Tech1 show fans requested on?

[LGAFF]

This keeps just getting better; just put in a different ECM and the same issue

[LGAFF]

So today I discovered that a on 90 and 92 the Tech one fan test mode works, but apparently not on a 91... Last year I took the car off the rack for a trial run after putting it back together, the fans did not come on and the car went up to 230+ degrees(tuned to turn on early)...so I shut if off and put it back on the rack in the garage

I got my tech one out, and tried to force the fans on, didnt work. I tried it on my 90, it worked... so went back to my 91 swapped the relays, still couldnt force them on.... put the car away until this year.

I had some time to work on the 91 again recently, tried the tech one on my 92 it worked to force them on... so I went back to the 91 tried to again always the same symptoms the relays would click, both primary and secondary fans would even turn on for a second or two sometimes..... I went through ecms. proms checks etc.. 90/92 eproms in the 91 always worked fans when placed in the 91... any 91 prom would never work, stock modded, etc

So today, took the car back outside... swapped the relays and what do you know they work, came on at 207

So big error on my part in assuming the Tech One inability to turn the fans on was an indicator of the problem with the car .....

[XfireZ51]

Wonder if u can confirm w someone like Marc.

[LGAFF]

Marc doesnt use a Tech One but he was nice enough to help me with prom testing....I got too stuck on my fans dont work and if it cant pass the test mode I need to keep looking vs retesting with a running car.... My assumption was if the fans work in my other two and they both allow the fans on then obviously I still have an issue, repeat.... hey it runs and the car is not mechanically completed....

[Corvette95]

regardless, I am glad you got it fixed. There is no known reason the Tech1 would not work as it does on the others. I wonder if you have a connector problem with the ALDL port on the 91. Also, I have had issues with an Tech1 cartridge having program issues. I assume you are using a Mass Storage Cartridge in your Tech1. When I was asking out the Data list showing the fan command, this is where I starting to troubleshoot. Good job on finding the root issue. Maybe next time you are with someone that has a Tech1 you can try theirs on your 91, unlikely but have seen it happen with a going bad cartridge. Also, may try using the 90 or 92 VIN on the Tech1 when connected to the 91.

[LGAFF]

The Tech one worked on the 90/92 and also the Tech one worked in the 91 with any combination of ECMS and even 90/92 chips in the 91 car, odd....

its in my video test....

Thanks for everyone for their input

[XfireZ51]

Lee,

I have a Tech One. Maybe we can try that and see if it is a Tech One issue.