240 OD instrument indicator

  • Thread starter Thread starter Randy G.
  • Start date Start date
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Randy G.

You may remember that we bought Mom an '85 240, with auto trans and
OD. It works fine and shifts great (and is getting over 22 mpg), but
the OD lamp on the dash works backwards:
OD on - Lamp on
OD off - Lamp off

The first guesses when I posted this originally was that it had the
incorrect relay. I hit the Pick 'n Pull and got another relay from
another auto trans, and it matched the numbers in the Vadis. I
resoldered the board on the replacement in preparation for R+R.
Yesterday I finally got the chance to get into the car and the relay
that was in there was the same white one (the relay for the stick is
red, auto is white, and it had the proper white one). I switched it
anyway, but no change.

So I dug into the wiring diagram in depth and here's my theory:

One side of the indicator lamp is fed +12v. from the fuse box to the
instrument cluster when the ignition is on. The other side of the lamp
goes to 87a on the OD relay. This connects internally to terminal 87
which leads to the OD solenoid on the tranny.

NORMAL OPERATION:
When the OD is off, the 12 volt feed from the cluster goes through
the lamp, to Relay terminal 87a, out through OD relay terminal 87, and
grounds through the OD solenoid's windings. There is nowhere near
enough current to activate the solenoid so the lamp is illuminated
telling the driver that OD is off.

When the OD is on, the relay is energized and 12 volts is fed to
the solenoid from terminal 15 on the OD relay, out through OD relay
terminal 87. Now +12 volts is being supplied at both sides of the
indicator lamp and so it is off now.

So it seems that there is a problem with the wiring in or to the
instrument cluster that is not supplying voltage to the indicator lamp
when the OD is off causing it to only illuminate when the OD is on. So
before I go chasing this....

Comments...?
__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"
 
Hi,
We have an 850 and a 2000 V70. The lamps on the dash for the cruise
control works just as your OD lamp works, namely cruise on - lamp on,
cruise off - lamp off. Maybe that is the way you OD lamp should be and
it is working correctly. We had an 82 245 with OD and I think it worked
the same way, but I can not remember for sure.
Good luck, Brad
 
Mystical said:
Maybe that is the way you OD lamp should be and
it is working correctly. We had an 82 245 with OD and I think it worked
the same way, but I can not remember for sure.
Click to expand...

Not at all.

The lamp on the dash says "OD off" (or words to that effect). The
manual states, "As a reminder, when 4th gear [which is the OD] is
disengaged, the indicator light in the instrument panel is
illuminated." So when the lamp is illuminated the OD is supposed to
be off. For most driving situations you never turn off the OD on the
240s, at least with the automatics:

from the manual:
---------------------
Disengage 4th gear (reminder light illuminated) when:
* towing a trailer
* driving on hilly roads where precise speed control is desired.
----------------------
.. IPD even sells a plate that you use to permanently disable the OD
since it can be expensive to repair when it does go out.


__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"
 
Randy said:
You may remember that we bought Mom an '85 240, with auto trans and
OD. It works fine and shifts great (and is getting over 22 mpg), but
the OD lamp on the dash works backwards:
OD on - Lamp on
OD off - Lamp off

The first guesses when I posted this originally was that it had the
incorrect relay. I hit the Pick 'n Pull and got another relay from
another auto trans, and it matched the numbers in the Vadis. I
resoldered the board on the replacement in preparation for R+R.
Yesterday I finally got the chance to get into the car and the relay
that was in there was the same white one (the relay for the stick is
red, auto is white, and it had the proper white one). I switched it
anyway, but no change.

So I dug into the wiring diagram in depth and here's my theory:

One side of the indicator lamp is fed +12v. from the fuse box to the
instrument cluster when the ignition is on. The other side of the lamp
goes to 87a on the OD relay. This connects internally to terminal 87
which leads to the OD solenoid on the tranny.

NORMAL OPERATION:
When the OD is off, the 12 volt feed from the cluster goes through
the lamp, to Relay terminal 87a, out through OD relay terminal 87, and
grounds through the OD solenoid's windings. There is nowhere near
enough current to activate the solenoid so the lamp is illuminated
telling the driver that OD is off.

When the OD is on, the relay is energized and 12 volts is fed to
the solenoid from terminal 15 on the OD relay, out through OD relay
terminal 87. Now +12 volts is being supplied at both sides of the
indicator lamp and so it is off now.

So it seems that there is a problem with the wiring in or to the
instrument cluster that is not supplying voltage to the indicator lamp
when the OD is off causing it to only illuminate when the OD is on. So
before I go chasing this....

Comments...?
__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"
Click to expand...



I would start by pulling the relay and measuring between the chassis
ground and 87a on the relay, or just ground 87a and see if the light
illuminates. That will tell you if things are ok on the cluster side.

It's worth checking the ground strap between the valve cover and
firewall too, flaky ground there can cause all sorts of bizarre
problems. The fuse box is a prime suspect as well, corroded fuse
contacts are a classic source of 240 gremlins.
 
James Sweet said:
I would start by pulling the relay and measuring between the chassis
ground and 87a on the relay, or just ground 87a and see if the light
illuminates. That will tell you if things are ok on the cluster side.

It's worth checking the ground strap between the valve cover and
firewall too, flaky ground there can cause all sorts of bizarre
problems. The fuse box is a prime suspect as well, corroded fuse
contacts are a classic source of 240 gremlins.
Click to expand...

Thank you, James. Will do that and report back as soon as I get a
chance to get my hands on the car again.
__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"
 
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