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post #1 of 9 (permalink) Old 08-21-2003, 01:50 PM Thread Starter
 
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No Reverse

Hey there, I just bought a 1985 Cougar yesterday. I knew it had a few problems, hopefully one of you guys can help me fix one of them. The car does not reverse. When shifted into reverse, it shifts properly but the engine just revs when gas is applied.
I've been told it might be a linkage problem, but that was not a sure bet. If linkage is however the problem, how do I fix that? This is really my first "project" car, so I'm a novice, and any help would be appreciated.
Thanks.
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post #2 of 9 (permalink) Old 08-21-2003, 02:08 PM
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moving to drivetrain.
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post #3 of 9 (permalink) Old 08-21-2003, 02:23 PM
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Welcome to the forums, Carla.

I did a very quick search here about no reverse (using No AND reverse as the search terms/parameters), and located a few posts that seem to agree about the linkage. Accoring to a Ford "Symptoms Chart," you also may want to check the transmission fluid level and color, to make sure it's ok (warm up the car for about 10 minutes, check the trans fluid level with the car level and running). The fluid should be on the dipstick, in the "hot" range, and appear a nice bright reddish color. If it's dark, the fluid should be changed. How many miles are on the car? It may be that a reverse gear component or two may be worn (servo, piston, clutch...)

I'm not well-versed in transmissions, so, someone else will probably help in posting about repairing the linkage, and what else to look for.

Good luck to you.

--Pete
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post #4 of 9 (permalink) Old 08-22-2003, 09:42 PM
 
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1. Make sure the manual shift lever on the tranny is actually moving to the reverse detent in the tranny. Bad shift linkage might be holding it half-off the detent, which is bad.

2. If it is, check the tranny line pressure in reverse - the PCM should set it to around 120 psi at idle in reverse, and this should increase to over 200 as you add throttle. It will be around 65 at idle in neutral and drive. If the pressure isn't going up in reverse, the MPLS is the first thing to check.

3. If the above are OK, its either valve body trouble (rare), or a burned reverse band, which means a rebuild.
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post #5 of 9 (permalink) Old 08-27-2003, 09:42 PM Thread Starter
 
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Where would I go about checking the PCM pressure? For future reference, what are MPLS and PCM acronyms for?
We checked the transmission fluid and added 1 qt because it was low, still no luck. Today the car was put into park on a hill and it started to roll backwards accompanied by a clicking noise. I'm starting to think this might be a big problem. We have yet to check the linkage.
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post #6 of 9 (permalink) Old 08-28-2003, 09:02 AM
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Quote:
Originally posted by Carla
Where would I go about checking the PCM pressure? For future reference, what are MPLS and PCM acronyms for?
MPLS= Manual Position Lever Sensor
From the service manual (c. 1994):

The manual lever position sensor (MLP sensor):

Is transmission-mounted.
The powertrain control module (PCM) (12A650) monitors the voltage across a series of step-down resistors that corresponds to the position of the manual control lever (7A256). The powertrain control module uses this information in determining desired gear and EPC pressure.
Permits the engine to start only in the PARK and NEUTRAL positions.
Activates the back-up lamps in the REVERSE position.

PCM=Powertrain Control Module

From the service manual (c. 1994):

The powertrain control module (PCM) (12A650) performs the following functions:

Accepts inputs from various engine sensors to compute the required fuel flow rate necessary to maintain a prescribed air/fuel ratio throughout the entire engine operational range.
Then the powertrain control module outputs a command to the fuel injectors (9F593) to meter the appropriate quantity of fuel.
Determines and compensates for the age of the vehicle and its uniqueness.
Automatically senses and compensates for changes in altitude (i.e. from sea level to mountains).

From what I've read, there's an additional pressure test tap on the 4R70W that tests EPC solenoid pressure. From the service manual (c. 1994): This Pinpoint Test is intended to diagnose the following components: Transmission Wiring Harness, EPC, EPCPWR, and Powertrain Control Module (PCM).


As to how to check the pressure, I cannot help much, but there's a line pressure tap on the housing that one can test pressure at. I cannot verify this on the 1985 transmission, though....

Last edited by IronChopz; 08-28-2003 at 09:08 AM.
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post #7 of 9 (permalink) Old 08-28-2003, 09:04 AM
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What transmission does a 1985 car have in it? Is it the AOD?

JH
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post #8 of 9 (permalink) Old 08-30-2003, 11:27 PM Thread Starter
 
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Pretty sure it's the AOD.
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post #9 of 9 (permalink) Old 08-30-2003, 11:55 PM
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Does it have overdrive?

Josh Keady

1994 Super Coupe ('93 5.0L swap), 1990 Tbird 3.8L, 1982 Honda CB900F, 1972 F-100 SportCustom 4x4, 1970 Chevy Custom Camper / 20
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