89 cherokee TCU
 

Anyone know how to get the TCU out from under the dash? I have been
having a shifting problem, that happens once or twice a week. I get
stuck in first after a long warmup or driving on the highway. I have
found that If I pull the TCU fuse I can shift manually. I see 5 volts
on the lead going to the TPS + (pin A on TPS connector) to a common
gnd. I see about 4.5 volts between TPS + and TPS gnd. (between pin a
nd D on TPS connector) About .5 volts between TPS gnd and common gnd.
Is this normal or could I have a bad ground on the TCU. Thanks

Jim

Re: 89 cherokee TCU
 

http://www.transonline.com/transdige...ers/index.html
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

downhill101@comcast.net wrote:
>
> Anyone know how to get the TCU out from under the dash? I have been
> having a shifting problem, that happens once or twice a week. I get
> stuck in first after a long warmup or driving on the highway. I have
> found that If I pull the TCU fuse I can shift manually. I see 5 volts
> on the lead going to the TPS + (pin A on TPS connector) to a common
> gnd. I see about 4.5 volts between TPS + and TPS gnd. (between pin a
> nd D on TPS connector) About .5 volts between TPS gnd and common gnd.
> Is this normal or could I have a bad ground on the TCU. Thanks
>
> Jim

Re: 89 cherokee TCU
 

http://www.transonline.com/transdige...ers/index.html
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

downhill101@comcast.net wrote:
>
> Anyone know how to get the TCU out from under the dash? I have been
> having a shifting problem, that happens once or twice a week. I get
> stuck in first after a long warmup or driving on the highway. I have
> found that If I pull the TCU fuse I can shift manually. I see 5 volts
> on the lead going to the TPS + (pin A on TPS connector) to a common
> gnd. I see about 4.5 volts between TPS + and TPS gnd. (between pin a
> nd D on TPS connector) About .5 volts between TPS gnd and common gnd.
> Is this normal or could I have a bad ground on the TCU. Thanks
>
> Jim

Re: 89 cherokee TCU
 

http://www.transonline.com/transdige...ers/index.html
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

downhill101@comcast.net wrote:
>
> Anyone know how to get the TCU out from under the dash? I have been
> having a shifting problem, that happens once or twice a week. I get
> stuck in first after a long warmup or driving on the highway. I have
> found that If I pull the TCU fuse I can shift manually. I see 5 volts
> on the lead going to the TPS + (pin A on TPS connector) to a common
> gnd. I see about 4.5 volts between TPS + and TPS gnd. (between pin a
> nd D on TPS connector) About .5 volts between TPS gnd and common gnd.
> Is this normal or could I have a bad ground on the TCU. Thanks
>
> Jim

Re: 89 cherokee TCU
 

Something is screwy with your readings maybe?....

With the throttle closed and the key in run/engine off, you should see a
little higher than 200 ma or 0.02V from one side to the center (ground I
think). With wide open throttle it should rise to close to 4.8V.

Your TPS should have a double output I think. The other side and center
should read opposite to the above, that side controls the tranny.

These readings are taken with the TPS plugged in and the plug back
probed with the meter.

Do you have any kind of radio transmitter in the vehicle? The TCU is
known to go insane from RF interference if any of the power or antenna
leads are close to it.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

downhill101@comcast.net wrote:
>
> Anyone know how to get the TCU out from under the dash? I have been
> having a shifting problem, that happens once or twice a week. I get
> stuck in first after a long warmup or driving on the highway. I have
> found that If I pull the TCU fuse I can shift manually. I see 5 volts
> on the lead going to the TPS + (pin A on TPS connector) to a common
> gnd. I see about 4.5 volts between TPS + and TPS gnd. (between pin a
> nd D on TPS connector) About .5 volts between TPS gnd and common gnd.
> Is this normal or could I have a bad ground on the TCU. Thanks
>
> Jim

Re: 89 cherokee TCU
 

Something is screwy with your readings maybe?....

With the throttle closed and the key in run/engine off, you should see a
little higher than 200 ma or 0.02V from one side to the center (ground I
think). With wide open throttle it should rise to close to 4.8V.

Your TPS should have a double output I think. The other side and center
should read opposite to the above, that side controls the tranny.

These readings are taken with the TPS plugged in and the plug back
probed with the meter.

Do you have any kind of radio transmitter in the vehicle? The TCU is
known to go insane from RF interference if any of the power or antenna
leads are close to it.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

downhill101@comcast.net wrote:
>
> Anyone know how to get the TCU out from under the dash? I have been
> having a shifting problem, that happens once or twice a week. I get
> stuck in first after a long warmup or driving on the highway. I have
> found that If I pull the TCU fuse I can shift manually. I see 5 volts
> on the lead going to the TPS + (pin A on TPS connector) to a common
> gnd. I see about 4.5 volts between TPS + and TPS gnd. (between pin a
> nd D on TPS connector) About .5 volts between TPS gnd and common gnd.
> Is this normal or could I have a bad ground on the TCU. Thanks
>
> Jim

Re: 89 cherokee TCU
 

Something is screwy with your readings maybe?....

With the throttle closed and the key in run/engine off, you should see a
little higher than 200 ma or 0.02V from one side to the center (ground I
think). With wide open throttle it should rise to close to 4.8V.

Your TPS should have a double output I think. The other side and center
should read opposite to the above, that side controls the tranny.

These readings are taken with the TPS plugged in and the plug back
probed with the meter.

Do you have any kind of radio transmitter in the vehicle? The TCU is
known to go insane from RF interference if any of the power or antenna
leads are close to it.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

downhill101@comcast.net wrote:
>
> Anyone know how to get the TCU out from under the dash? I have been
> having a shifting problem, that happens once or twice a week. I get
> stuck in first after a long warmup or driving on the highway. I have
> found that If I pull the TCU fuse I can shift manually. I see 5 volts
> on the lead going to the TPS + (pin A on TPS connector) to a common
> gnd. I see about 4.5 volts between TPS + and TPS gnd. (between pin a
> nd D on TPS connector) About .5 volts between TPS gnd and common gnd.
> Is this normal or could I have a bad ground on the TCU. Thanks
>
> Jim