Lorenfb

"It does look a bit like a fuse type resistor."

Guess again, it's a simple power resistor that got a little hot (most likely O.K)
when someone connected a battery charger to a totally dead battery with
the key 'on', i.e. Can cause > 18 volts.

salukijac

Sorry guys...nice afternoon so I went golfing. Here's the underside. Nothing tale telling.

Attachment 454310

I do have a Bentley and it does have a schematic for the cruise control and the 86-87 are different than the 88-89. I'll probably try to do the troubleshooting tomorrow after work. As a matter of fact I have a report due to the boss tonight and should get on it.

theiceman

that doesn't look too bad. i would try swapping into another car to verify of it is bad .. sorry have not read the entire thread, so maybe you did that already

dshepp806

swap out would certainly "cut to the chase".

Bottom solder looks OK (best as can tell from pics)......

Should you desire the checksheet for the 89, just let me know,..although I've reservations on pinout...maybe Loren can expound on this for us?

Best,

Doyle

dshepp806

Surely, someone here has the Bentley section for this gent's car? No?

Doyle

rusnak

I would say probably the troubleshooting guide. Unless the external connections gives values that you can use to test the module. Thanks, 1986 Targa. I am dyin here cause I can't find my service manual.

dshepp806

MY 89 was in a table,.....how does it show it in the Bentley for Salukijac's model?

Doyle

salukijac

I have a Bentley that covers 84 through 89 and it only has one troubleshooting table for all years, so I think I have what I need as far as TS table.

There is a Cruise control schematic but not for the module. The way I see it, after T/Sing if it points to the module my only opton is to send it out for repairs.

salukijac

Yep...that's exactly what I have.

Lorenfb

"I have a Bentley that covers 84 through 89 and it only has one troubleshooting table for all years, so I think I have what I need as far as TS table."

Remember, the early and late CCs are totally different, i.e. early - analog,
late - digital.

salukijac

So looking at the Troubleshooting Chart there is only one check that could remotely point to the module? "Connect Ohmmeter between terminal 11 and ground and turn the rear wheels." Actually not even as the module is disconnected. Every other step identifies other components (e.g., pedal switch, servo, etc).

Loren don't you have T/S instructions other than the one identified in the Bentley that I can perform to isolate the module? Or is it normally part of the module repair fee to diagnose whether the module is good or bad? If I remember correctly the last time I was on your site I remember seeing intructions for DME Modules...I think.

Lorenfb

"Loren don't you have T/S instructions other than the one identified in the Bentley that I can perform to isolate the module?"

Actually, that one is fairly extensive.

The key areas I check to isolate the CC ECU are:

1. Check that both the brake & clutch switches are O.K.
i.e. use test light to check for proper brake & clutch sw. grds
2. Momentarily power (12V) the vacuum actuator (pins 3 & 7) while
running the engine (motor will accelerate).
3. Check speedo signal with LED test light with wheels turning
4. Check with test light for all the column switch inputs.
5. Check for main grounds with test light at 12V (clip test light to battery +)

Typical failure modes:
a. fails to hold speed once accel sw. is released
b. speed slowly decreases from set speed
c. vehicle never accels with accel switch

rusnak

between Gerry (86 Targa) and Loren, that's pretty good stuff right there.

dshepp806

Good stuff, Loren. Thanks for providing it.....the inputs should be easy enough HOWEVER determining what has failed in that PC board will be another matter without some really good knowledge of the circuit's operation (for the OP).

Still good contribution from you. Thanks.

Doyle

Lorenfb

"HOWEVER determining what has failed in that PC board will be another matter without some really good knowledge of the circuit's operation (for the OP)."

Needs to be tested dynamically, i.e. with a signal generator and scope.
The 'shotgun' parts changing, just like fixing an engine problem, 'Won't
get it'.