1990 Grand Prix Problems!!!!

Hi. I have a few problems/questions for anyone how can help.

First off I have bought a 1990/91 grand prix le with a 3.1L V-6 for winter and I need some help.
1. My transmission shifts hard when going into reverse and a little bit
less rough when downshifting when coming to a stop, but it has no
problems in the forward gears and when downshifting for
acceleration. Any ideas or suggestions on smoothing things out.
2. The fan for the hvac system goes on and off with no apparent pattern
in terms of when and why this happens. I have wiggled all the wires
and fuses in the passenger footwell and the fan did come on once
but I have not been able to do it consistently. Also the fan does not
blow very hard on the max setting when it is working.
3. The low coolant light and the check/service engine soon lights come
on and stat on even though the coolant is full and the engine runs
fine?! Anyone know what may be causing this?

Since I have already sunk a lot of money into this car I am not giving up and I appreciate any help or suggestions that anybody may have.
Thanks.

1. The 91 Grand Prix used both an electronic shifted trans and one that uses a vacuum modulator that controls shifts. Give me the last 8 digits of your vin so we can determine what trans you have.
2. The blower problem is either the blower motor itself drawing too many amps or the blower resistor.
3. Have Auto-Zone or Advance pull the codes tripping the check engine light (they do it for free) and post the results.

Thanks for the response.
The last 8 digits of the VIN are LF230954.
Also who are Auto-Zone and Advance. I am in Alberta, Canada.
I will check out the HVAC info.


1. The 91 Grand Prix used both an electronic shifted trans and one that uses a vacuum modulator that controls shifts. Give me the last 8 digits of your vin so we can determine what trans you have.
2. The blower problem is either the blower motor itself drawing too many amps or the blower resistor.
3. Have Auto-Zone or Advance pull the codes tripping the check engine light (they do it for free) and post the results.

Sorry, auto-Zone and Advance are parts stores here in the US that offer free "check engine" diagnosis. As far as the vin, your 1990 is too old to run the vin (the GM computer only has vin info back to 1991). If your SPID (Service Parts IDentification) label is still in the trunk(look on the underside of the trunk lid or under the carpet on the spare tire well divider), for one of two codes: ME9 is the vacuum shifted trans
M13 is the electronic shifted trans

Hi. I found the ME9 code on the list. I have since posting noticed that
the transmission shifts hard if you go down more than one gear. Part
throttle acceleration is fine but if I step on it not so nice. I hope this
tranny holds up for 6 months :banghead:
Thanks again.


Sorry, auto-Zone and Advance are parts stores here in the US that offer free "check engine" diagnosis. As far as the vin, your 1990 is too old to run the vin (the GM computer only has vin info back to 1991). If your SPID (Service Parts IDentification) label is still in the trunk(look on the underside of the trunk lid or under the carpet on the spare tire well divider), for one of two codes: ME9 is the vacuum shifted trans
M13 is the electronic shifted trans

Vacuum leak?

Hi. Do you by any chance know where the blower resistor is located.
I have got one from G.M. and the service tech there thinks that is what
is causing the problem. They want $80 to install this part and I am
pretty sure that I can do this myself if I know where to look.

Thanks.


1. The 91 Grand Prix used both an electronic shifted trans and one that uses a vacuum modulator that controls shifts. Give me the last 8 digits of your vin so we can determine what trans you have.
2. The blower problem is either the blower motor itself drawing too many amps or the blower resistor.
3. Have Auto-Zone or Advance pull the codes tripping the check engine light (they do it for free) and post the results.

Hi. Do you by any chance know where the blower resistor is located.
I have got one from G.M. and the service tech there thinks that is what
is causing the problem. They want $80 to install this part and I am
pretty sure that I can do this myself if I know where to look.

Thanks.
I have the same problem with the A/C, and after a few times of messing with it I found out that the blower fan was faulty. I went as far as taking the blower fan out. I found that the connection on the fan blower, (not the connector on the wire), but the metal connection on the blower itself was bad. Your best bet is to go to a junkyard and get another blower motor for about $25-$35. Hope this works for you.

check the vacuum hose running to the modulator to see if there is trans fluid present. If there is, the diaphragm is ruptured causing your shift problem.
The blower motor resistor is mounted next to the blower motor on the passenger side of the car under the glove box.