J-Gate Gear Indication - I Was Less Correct Than Usual
#1
07-01-2017, 02:53 PM
J-Gate Gear Indication - I Was Less Correct Than Usual
Greetings All,
In several threads, typically about a starter that won't turn on, I've talked about the N and P indications on the J-gate bezel. After doing some more research, I think I may have had the details wrong.
I was under the impression that the P, N, D, R, etc. indicators were controlled by the transmission range selector on the transmission, as opposed to the shift lever location. In other words, if the cable broke, the indicators would show whatever gear the transmission was in. Moving the shift lever would not change the indication lights at the J-gate.
Now I'm not so sure. I was looking at the wiring diagram for the 5-speed (used on early models) and the transmission range selector does not appear to feed back any info to the J-gate if P or N is selected. The only thing I see for P or N on the transmission is an interlock circuit for the starter. If I'm reading that correctly, that means the J-gate indicators must be controlled by the position of the shift lever itself.
Later models (6-speed) looks to have an entirely different arrangement. Early models only have a powertrain control module for the engine and transmission. The later models have a separate transmission control module and a different type of gear position switch. The wiring diagram doesn't show any internal details, but it appears to have 4 proximity switches, not mechanical contacts like on the early models. The later model switch assembly may be a lot more "electronicky" than the earlier version.
So I'm still not 100% sure how it all works, but wanted to get the word out that my previous theory is probably wrong. Sorry for any confusion this may have caused.
Wiring diagrams here, see section 4.1 for the transmission:
JagRepair.com - Jaguar Repair Information Resource
In several threads, typically about a starter that won't turn on, I've talked about the N and P indications on the J-gate bezel. After doing some more research, I think I may have had the details wrong.
I was under the impression that the P, N, D, R, etc. indicators were controlled by the transmission range selector on the transmission, as opposed to the shift lever location. In other words, if the cable broke, the indicators would show whatever gear the transmission was in. Moving the shift lever would not change the indication lights at the J-gate.
Now I'm not so sure. I was looking at the wiring diagram for the 5-speed (used on early models) and the transmission range selector does not appear to feed back any info to the J-gate if P or N is selected. The only thing I see for P or N on the transmission is an interlock circuit for the starter. If I'm reading that correctly, that means the J-gate indicators must be controlled by the position of the shift lever itself.
Later models (6-speed) looks to have an entirely different arrangement. Early models only have a powertrain control module for the engine and transmission. The later models have a separate transmission control module and a different type of gear position switch. The wiring diagram doesn't show any internal details, but it appears to have 4 proximity switches, not mechanical contacts like on the early models. The later model switch assembly may be a lot more "electronicky" than the earlier version.
So I'm still not 100% sure how it all works, but wanted to get the word out that my previous theory is probably wrong. Sorry for any confusion this may have caused.
Wiring diagrams here, see section 4.1 for the transmission:
JagRepair.com - Jaguar Repair Information Resource
Last edited by kr98664; 07-02-2017 at 10:54 AM.
The following 3 users liked this post by kr98664:
#2
07-11-2017, 12:40 PM
#3
07-11-2017, 09:59 PM
Yes, Joe, that is fantastic information. Thanks so much.
This is very interesting, at least to me. On the 6 speed models, the P, R, N, and D indications are feedback originating at the transmission. The 2-5 indications come from the J-gate. So I was only half wrong about being less correct than usual, at least on later cars. Since the conversations about these lights usually involve a starter that won't engage, it's good to know the source of the P or N safety interlock signal.
What document was that? I'd love to see the equivalent for the early 5-speed models. One big difference is the shift cable interface on the J-gate's left side (manual gear selection). On the 6-speed, the manual gear selection (2-5) is done by electronic switchery within the J-gate. The cable never moves beyond the D position.
On the 5-speed version, the J-gate moves the cable when the lever is on the left side. However, the cable doesn't move when the lever is moved to the side from D to 4. There's just a microswitch in the J-gate for that shift. But when the lever is moved forward from there, the cable does move for that.
This is very interesting, at least to me. On the 6 speed models, the P, R, N, and D indications are feedback originating at the transmission. The 2-5 indications come from the J-gate. So I was only half wrong about being less correct than usual, at least on later cars. Since the conversations about these lights usually involve a starter that won't engage, it's good to know the source of the P or N safety interlock signal.
What document was that? I'd love to see the equivalent for the early 5-speed models. One big difference is the shift cable interface on the J-gate's left side (manual gear selection). On the 6-speed, the manual gear selection (2-5) is done by electronic switchery within the J-gate. The cable never moves beyond the D position.
On the 5-speed version, the J-gate moves the cable when the lever is on the left side. However, the cable doesn't move when the lever is moved to the side from D to 4. There's just a microswitch in the J-gate for that shift. But when the lever is moved forward from there, the cable does move for that.
Last edited by kr98664; 07-11-2017 at 10:06 PM.
#4
07-12-2017, 12:58 AM
Veteran Member
May be from http://www.jagrepair.com/images/Auto...ning-guide.pdf (see under Auto Transmission)
Whether it's definitely the same for the S-Type I don't know.
Whether it's definitely the same for the S-Type I don't know.
#6
07-13-2017, 05:52 AM
Veteran Member
#7
07-13-2017, 06:07 PM
More good stuff there. I wish it had more info about the indicator lights, though. If anybody with the 5 speed auto ever has the shift cable disconnected for any reason, I'd love some feedback on how the lights behave.