Cruise control stopped working when I hit a dip in the road at highway speed. Cruise light out and will not come on. Checked at plug to control unit and signal is getting to plug when cruise activation switch is pushed. Power is getting to the cruise light circuit when the ignition is on. Fuses all appear to be good. Do I have a bad control?? Pulled the PCB out of the cruise control and found no obvious problems. Actually looks pristine

 

Stop lights working?

V6 or 4 cylinder?

The cruise light always has power, the return power runs through the ECU then to ground.

If the cruise light does not come on may be:

Bulb
Cruise ECU
Wiring issue, bad connection, etc.
Instrument circuit board for dash

Since the light went out when hitting a dip suspect a wire plug issue.

Return wire for bulb to ECU from dash console circuit board might be Orange. Runs to terminal 10 (PL) of ECU and to a data link connector. Then from terminal 16 of ECU to ground (White/Black wire). The White/Black wire should be grounded.

Red/Black is the power wire from the ECU-IG fuse.

Gauge fuse powers the cruise light.

 

Stop lights working? YES

V6 or 4 cylinder? 4 CYL

The cruise light always has power, the return power runs through the ECU then to ground. 12VDC at terminal 4 ECU plug with ignition switch on. I believe this is normal

If the cruise light does not come on may be:

Bulb I believe bulb is good based on above
Cruise ECU Could be. Not sure how to test other than eliminate any other possibility
Wiring issue, bad connection, etc. This was my initial thought and I would like to prove/find it
Instrument circuit board for dash.

Since the light went out when hitting a dip suspect a wire plug issue. I Agree

Return wire for bulb to ECU from dash console circuit board might be Orange. Runs to terminal 10 (PL) of ECU and to a data link connector. Then from terminal 16 of ECU to ground (White/Black wire). The White/Black wire should be grounded. In the diagram that I have power for light circuit comes from Gauge fuse through indicator light from pin 10 of combination meter(light). to Pin 4 of C15 plug on ECU I have 12VDC here with ignition on. Measuring resistance to ground at pin 11 of ECU (CMS) when cruise activation switch is pushed gives me 5.5 ohms. Seems a bit high to me but I have no experience here and am not sure if it should be less or not. Based on all of this I am almost ready to say that the ECU is bad. The only thing that I always come back to is how the failure happened.

Is there anything else I am missing before I spring for a new (or used) ECU

 

Looking the diagram when the cruise switch is on Pin 11 should be grounded.

Perhaps a bad ground or issue with the switch.

Check the resistance to ground at the ECU ground wire, Pin 16. Should be 0 ohm, if the same as Pin 11 may be a bad common ground point.

If 0 ohms there is a problem with the Pin 11 circuit.

If the 5.5 ohm resistance is high enough to cause problems don't know but best to investigate.

 

Checked resistance to ground from plug Pin 11 with switch on. 5.5 ohms
Checked resistance to ground from plug Pin 16 4.7 ohms
Checked resistance to ground from Junction connector J7 to ground 4.3 ohms
Checked resistance from plug Pin 16 to connector J11 and had 0.3 ohms with connector apart and 3.8 ohms with connector connected measuring resistance through the connector. Inspected connector and found that it looked very good. Gave it a cleaning and still the same 3.8 ohm result. Put everything back together and still have the original problem. I am now inclined to believe that the 4.7 ohms to ground from Pin 16 is normal. May see if I can source a male plug to replace male portion of J11.
Looks more like the ECU module all the time. Will post again if more developments.
will have to wait to decide whether to spring for a new ECU

 

What color is Pin 16, should white/black. This is the ground connection, should be 0 ohms.

If cruise switch on, Pin 11 should connect to the same junction box (J7) as Pin 16, then ground.

One of the wires at J7 must be grounded (J7 being a common ground collection point) and as such 0 ohms.

For an ECU try Ebay.

 

[quote=toyomoho;66139]What color is Pin 16, should white/black. This is the ground connection, should be 0 ohms. The wire is white/black. Actual resistance measures approx 5 ohms to ground

If cruise switch on, Pin 11 should connect to the same junction box (J7) as Pin 16, then ground. Again with switch on the resistance is approximately 5 ohms to ground

One of the wires at J7 must be grounded (J7 being a common ground collection point) and as such 0 ohms./quote] I followed the circuit all the way to the ground point at J11. It is here that I have I thought I may have a ground problem. In order to test I attached another ground to Pin 16 of the ECU. I still do not get the cruise light to come on. It is looking more all the time as if the ECU is the problem. I am now looking for a used module. Ebay and local salvage yard are both possibilities.
If anyone out there can think of anything else all suggestions welcome. I will update when (and if) I get this fixed
Thanks for the help.

 

Bought a used electronic unit rom a scrap dealer out of a 2001 Solara, which had a different part number for some reason, plugged it in and has been working since.